diff --git a/packages/bridge-controller/CHANGELOG.md b/packages/bridge-controller/CHANGELOG.md
index e67eb4cb00..56d510f43f 100644
--- a/packages/bridge-controller/CHANGELOG.md
+++ b/packages/bridge-controller/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- **BREAKING**: Add persisted input primary denomination state and `Unified SwapBridge Fiat Crypto Toggle Clicked` analytics event support ([#9147](https://github.com/MetaMask/core/pull/9147))
+
 ## [75.2.1]
 
 ### Changed
diff --git a/packages/bridge-controller/src/__snapshots__/bridge-controller.sse.batch.test.ts.snap b/packages/bridge-controller/src/__snapshots__/bridge-controller.sse.batch.test.ts.snap
index 0ee671c741..b1d5c0c009 100644
--- a/packages/bridge-controller/src/__snapshots__/bridge-controller.sse.batch.test.ts.snap
+++ b/packages/bridge-controller/src/__snapshots__/bridge-controller.sse.batch.test.ts.snap
@@ -10,6 +10,7 @@ exports[`BridgeController BatchSell (multiple quote requests) SSE fetch quotes s
   },
   "batchSellTrades": null,
   "batchSellTradesLoadingStatus": 0,
+  "inputPrimaryDenomination": "token_amount",
   "minimumBalanceForRentExemptionInLamports": "0",
   "quoteFetchError": null,
   "quoteRequest": [
@@ -112,6 +113,7 @@ exports[`BridgeController BatchSell (multiple quote requests) SSE fetch quotes s
       "custom_slippage": true,
       "feature_id": "batch_sell",
       "has_sufficient_funds": true,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
diff --git a/packages/bridge-controller/src/__snapshots__/bridge-controller.sse.test.ts.snap b/packages/bridge-controller/src/__snapshots__/bridge-controller.sse.test.ts.snap
index 76019e0e68..af4e3ba7e7 100644
--- a/packages/bridge-controller/src/__snapshots__/bridge-controller.sse.test.ts.snap
+++ b/packages/bridge-controller/src/__snapshots__/bridge-controller.sse.test.ts.snap
@@ -76,6 +76,7 @@ exports[`BridgeController SSE should replace all stale quotes after a refresh an
     "custom_slippage": true,
     "feature_id": "unified_swap_bridge",
     "has_sufficient_funds": true,
+    "input_primary_denomination": "token_amount",
     "is_hardware_wallet": false,
     "location": "Main View",
     "security_warnings": [],
@@ -105,6 +106,7 @@ exports[`BridgeController SSE should reset and refetch quotes after quote reques
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": false,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
@@ -134,6 +136,7 @@ exports[`BridgeController SSE should reset quotes list if quote refresh fails 2`
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": true,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
@@ -188,6 +191,7 @@ exports[`BridgeController SSE should rethrow error from server 1`] = `
   },
   "batchSellTrades": null,
   "batchSellTradesLoadingStatus": null,
+  "inputPrimaryDenomination": "token_amount",
   "minimumBalanceForRentExemptionInLamports": "0",
   "quoteFetchError": null,
   "quoteRequest": [
@@ -266,6 +270,7 @@ exports[`BridgeController SSE should rethrow error from server 3`] = `
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": true,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
@@ -320,6 +325,7 @@ exports[`BridgeController SSE should trigger quote polling if request is valid 1
   },
   "batchSellTrades": null,
   "batchSellTradesLoadingStatus": null,
+  "inputPrimaryDenomination": "token_amount",
   "minimumBalanceForRentExemptionInLamports": "0",
   "quoteFetchError": null,
   "quoteRequest": [
@@ -398,6 +404,7 @@ exports[`BridgeController SSE should trigger quote polling if request is valid 2
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": true,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
diff --git a/packages/bridge-controller/src/__snapshots__/bridge-controller.test.ts.snap b/packages/bridge-controller/src/__snapshots__/bridge-controller.test.ts.snap
index 3b2eceb75a..883571bd07 100644
--- a/packages/bridge-controller/src/__snapshots__/bridge-controller.test.ts.snap
+++ b/packages/bridge-controller/src/__snapshots__/bridge-controller.test.ts.snap
@@ -10,6 +10,7 @@ exports[`BridgeController should handle errors from fetchBridgeQuotes 1`] = `
   },
   "batchSellTrades": null,
   "batchSellTradesLoadingStatus": null,
+  "inputPrimaryDenomination": "token_amount",
   "minimumBalanceForRentExemptionInLamports": "0",
   "quoteFetchError": null,
   "quoteRequest": [
@@ -43,6 +44,7 @@ exports[`BridgeController should handle errors from fetchBridgeQuotes 2`] = `
   },
   "batchSellTrades": null,
   "batchSellTradesLoadingStatus": null,
+  "inputPrimaryDenomination": "token_amount",
   "minimumBalanceForRentExemptionInLamports": "0",
   "quoteFetchError": null,
   "quoteRequest": [
@@ -345,6 +347,29 @@ exports[`BridgeController trackUnifiedSwapBridgeEvent client-side calls should t
 ]
 `;
 
+exports[`BridgeController trackUnifiedSwapBridgeEvent client-side calls should track the FiatCryptoToggleClicked event 1`] = `
+[
+  [
+    "Unified SwapBridge Fiat Crypto Toggle Clicked",
+    {
+      "action_type": "swapbridge-v1",
+      "chain_id_destination": "eip155:1",
+      "chain_id_source": "eip155:1",
+      "feature_id": "quick_buy_follow_trading",
+      "location": "Main View",
+      "new_primary_denomination": "fiat_value",
+      "previous_primary_denomination": "token_amount",
+      "swap_type": "single_chain",
+      "token_address_destination": "eip155:1/erc20:0xdAC17F958D2ee523a2206206994597C13D831ec7",
+      "token_address_source": "eip155:1/slip44:60",
+      "token_security_type_destination": null,
+      "token_symbol_destination": "USDC",
+      "token_symbol_source": "ETH",
+    },
+  ],
+]
+`;
+
 exports[`BridgeController trackUnifiedSwapBridgeEvent client-side calls should track the InputSourceDestinationFlipped event 1`] = `
 [
   [
@@ -379,6 +404,7 @@ exports[`BridgeController trackUnifiedSwapBridgeEvent client-side calls should t
       "chain_id_source": "eip155:1",
       "custom_slippage": false,
       "feature_id": "quick_buy_token_details",
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "slippage_limit": undefined,
@@ -454,6 +480,7 @@ exports[`BridgeController trackUnifiedSwapBridgeEvent client-side calls should t
       "gas_included_7702": false,
       "has_gas_included_quote": false,
       "initial_load_time_all_quotes": 0,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "price_impact": 0,
@@ -530,6 +557,7 @@ exports[`BridgeController updateBridgeQuoteRequestParams should only poll once i
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": false,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
@@ -560,6 +588,7 @@ exports[`BridgeController updateBridgeQuoteRequestParams should only poll once i
       "gas_included_7702": false,
       "has_gas_included_quote": false,
       "initial_load_time_all_quotes": 11000,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "price_impact": 0,
@@ -854,6 +883,7 @@ exports[`BridgeController updateBridgeQuoteRequestParams should trigger quote po
   "assetExchangeRates": {},
   "batchSellTrades": null,
   "batchSellTradesLoadingStatus": null,
+  "inputPrimaryDenomination": "token_amount",
   "minimumBalanceForRentExemptionInLamports": "0",
   "quoteFetchError": null,
   "quoteRequest": [
@@ -891,6 +921,7 @@ exports[`BridgeController updateBridgeQuoteRequestParams should trigger quote po
   },
   "batchSellTrades": null,
   "batchSellTradesLoadingStatus": null,
+  "inputPrimaryDenomination": "token_amount",
   "minimumBalanceForRentExemptionInLamports": "0",
   "quoteFetchError": null,
   "quoteRequest": [
@@ -968,6 +999,7 @@ exports[`BridgeController updateBridgeQuoteRequestParams should trigger quote po
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": true,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
@@ -993,6 +1025,7 @@ exports[`BridgeController updateBridgeQuoteRequestParams should trigger quote po
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": true,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
@@ -1018,6 +1051,7 @@ exports[`BridgeController updateBridgeQuoteRequestParams should trigger quote po
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": true,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
@@ -1069,6 +1103,7 @@ exports[`BridgeController updateBridgeQuoteRequestParams should trigger quote po
       "custom_slippage": true,
       "feature_id": "unified_swap_bridge",
       "has_sufficient_funds": true,
+      "input_primary_denomination": "token_amount",
       "is_hardware_wallet": false,
       "location": "Main View",
       "security_warnings": [],
diff --git a/packages/bridge-controller/src/bridge-controller-method-action-types.ts b/packages/bridge-controller/src/bridge-controller-method-action-types.ts
index 12a7527abd..3b0e41fcda 100644
--- a/packages/bridge-controller/src/bridge-controller-method-action-types.ts
+++ b/packages/bridge-controller/src/bridge-controller-method-action-types.ts
@@ -25,6 +25,11 @@ export type BridgeControllerSetLocationAction = {
   handler: BridgeController['setLocation'];
 };
 
+export type BridgeControllerSetInputPrimaryDenominationAction = {
+  type: `BridgeController:setInputPrimaryDenomination`;
+  handler: BridgeController['setInputPrimaryDenomination'];
+};
+
 export type BridgeControllerResetStateAction = {
   type: `BridgeController:resetState`;
   handler: BridgeController['resetState'];
@@ -53,6 +58,7 @@ export type BridgeControllerMethodActions =
   | BridgeControllerFetchQuotesAction
   | BridgeControllerStopPollingForQuotesAction
   | BridgeControllerSetLocationAction
+  | BridgeControllerSetInputPrimaryDenominationAction
   | BridgeControllerResetStateAction
   | BridgeControllerSetChainIntervalLengthAction
   | BridgeControllerTrackUnifiedSwapBridgeEventAction
diff --git a/packages/bridge-controller/src/bridge-controller.test.ts b/packages/bridge-controller/src/bridge-controller.test.ts
index 3264079bce..126f66ce2b 100644
--- a/packages/bridge-controller/src/bridge-controller.test.ts
+++ b/packages/bridge-controller/src/bridge-controller.test.ts
@@ -3013,6 +3013,56 @@ describe('BridgeController', function () {
       });
     });
 
+    it('should track the FiatCryptoToggleClicked event', async () => {
+      await withController(async ({ rootMessenger, controller }) => {
+        jest.spyOn(console, 'warn').mockImplementationOnce(jest.fn());
+        await rootMessenger.call(
+          'BridgeController:updateBridgeQuoteRequestParams',
+          {
+            walletAddress: '0x123',
+          },
+          {
+            stx_enabled: false,
+            security_warnings: [],
+            token_symbol_source: 'ETH',
+            token_symbol_destination: 'USDC',
+            usd_amount_source: 100,
+            token_security_type_destination: null,
+            feature_id: FeatureId.QUICK_BUY_FOLLOW_TRADING,
+          },
+        );
+        rootMessenger.call(
+          'BridgeController:setInputPrimaryDenomination',
+          'fiat_value',
+        );
+        expect(controller.state.inputPrimaryDenomination).toBe('fiat_value');
+        jest.clearAllMocks();
+        rootMessenger.call(
+          'BridgeController:trackUnifiedSwapBridgeEvent',
+          UnifiedSwapBridgeEventName.FiatCryptoToggleClicked,
+          {
+            location: MetaMetricsSwapsEventSource.MainView,
+            previous_primary_denomination: 'token_amount',
+            new_primary_denomination: 'fiat_value',
+            token_symbol_source: 'ETH',
+            token_symbol_destination: 'USDC',
+            chain_id_source: formatChainIdToCaip(ChainId.ETH),
+            chain_id_destination: formatChainIdToCaip(ChainId.ETH),
+            token_address_source: formatAddressToAssetId('', ChainId.ETH),
+            token_address_destination: formatAddressToAssetId(
+              ETH_USDT_ADDRESS,
+              ChainId.ETH,
+            ),
+            token_security_type_destination: null,
+            swap_type: MetricsSwapType.SINGLE,
+            feature_id: FeatureId.QUICK_BUY_FOLLOW_TRADING,
+          },
+        );
+        expect(trackMetaMetricsFn).toHaveBeenCalledTimes(1);
+        expect(trackMetaMetricsFn.mock.calls).toMatchSnapshot();
+      });
+    });
+
     it('should track InputChanged with an enum quick amount preset label', async () => {
       await withController(async ({ rootMessenger }) => {
         // Ignore console.warn for this test bc there will be expected asset rate fetching warnings
@@ -4342,6 +4392,7 @@ describe('BridgeController', function () {
             "assetExchangeRates": {},
             "batchSellTrades": null,
             "batchSellTradesLoadingStatus": null,
+            "inputPrimaryDenomination": "token_amount",
             "minimumBalanceForRentExemptionInLamports": "0",
             "quoteFetchError": null,
             "quoteRequest": [
@@ -4370,7 +4421,11 @@ describe('BridgeController', function () {
             bridgeController.metadata,
             'persist',
           ),
-        ).toMatchInlineSnapshot(`{}`);
+        ).toMatchInlineSnapshot(`
+          {
+            "inputPrimaryDenomination": "token_amount",
+          }
+        `);
       });
     });
 
@@ -4387,6 +4442,7 @@ describe('BridgeController', function () {
             "assetExchangeRates": {},
             "batchSellTrades": null,
             "batchSellTradesLoadingStatus": null,
+            "inputPrimaryDenomination": "token_amount",
             "minimumBalanceForRentExemptionInLamports": "0",
             "quoteFetchError": null,
             "quoteRequest": [
diff --git a/packages/bridge-controller/src/bridge-controller.ts b/packages/bridge-controller/src/bridge-controller.ts
index 3c9f49378e..da33641ba9 100644
--- a/packages/bridge-controller/src/bridge-controller.ts
+++ b/packages/bridge-controller/src/bridge-controller.ts
@@ -35,6 +35,7 @@ import type {
   BridgeControllerState,
   BridgeControllerMessenger,
   FetchFunction,
+  InputPrimaryDenomination,
 } from './types';
 import { getAssetIdsForToken, toExchangeRates } from './utils/assets';
 import { hasSufficientBalance } from './utils/balance';
@@ -156,6 +157,12 @@ const metadata: StateMetadata<BridgeControllerState> = {
     includeInDebugSnapshot: false,
     usedInUi: true,
   },
+  inputPrimaryDenomination: {
+    includeInStateLogs: true,
+    persist: true,
+    includeInDebugSnapshot: false,
+    usedInUi: true,
+  },
   quoteStreamComplete: {
     includeInStateLogs: true,
     persist: false,
@@ -195,6 +202,7 @@ const MESSENGER_EXPOSED_METHODS = [
   'updateBatchSellTrades',
   'stopPollingForQuotes',
   'setLocation',
+  'setInputPrimaryDenomination',
   'resetState',
   'setChainIntervalLength',
   'trackUnifiedSwapBridgeEvent',
@@ -711,6 +719,14 @@ export class BridgeController extends StaticIntervalPollingController<BridgePoll
     this.#location = location;
   };
 
+  setInputPrimaryDenomination = (
+    inputPrimaryDenomination: InputPrimaryDenomination,
+  ) => {
+    this.update((state) => {
+      state.inputPrimaryDenomination = inputPrimaryDenomination;
+    });
+  };
+
   resetState = (
     reason = AbortReason.ResetState,
     quoteRequestIndex: number | null = null,
@@ -1155,6 +1171,9 @@ export class BridgeController extends StaticIntervalPollingController<BridgePoll
       location: clientProps?.location ?? this.#location,
       action_type: MetricsActionType.SWAPBRIDGE_V1,
     };
+    const inputPrimaryDenominationProperties = {
+      input_primary_denomination: this.state.inputPrimaryDenomination,
+    };
     const quoteRequest = this.state.quoteRequest[quoteRequestIndex];
     switch (eventName) {
       case UnifiedSwapBridgeEventName.ButtonClicked:
@@ -1172,6 +1191,16 @@ export class BridgeController extends StaticIntervalPollingController<BridgePoll
             this.state.tokenSecurityTypeDestination,
           ),
           ...this.#getRequestMetadata(),
+          ...inputPrimaryDenominationProperties,
+          ...baseProperties,
+        };
+      case UnifiedSwapBridgeEventName.FiatCryptoToggleClicked:
+        return {
+          ...getRequestParams(
+            quoteRequest,
+            this.state.tokenSecurityTypeDestination,
+          ),
+          swap_type: getSwapTypeFromQuote(quoteRequest),
           ...baseProperties,
         };
       case UnifiedSwapBridgeEventName.QuotesValidationFailed:
@@ -1192,6 +1221,7 @@ export class BridgeController extends StaticIntervalPollingController<BridgePoll
           ...this.#getRequestMetadata(),
           ...this.#getQuoteFetchData(),
           refresh_count: this.state.quotesRefreshCount,
+          ...inputPrimaryDenominationProperties,
           ...baseProperties,
         };
       case UnifiedSwapBridgeEventName.QuotesRequested:
@@ -1202,6 +1232,7 @@ export class BridgeController extends StaticIntervalPollingController<BridgePoll
           ),
           ...this.#getRequestMetadata(),
           has_sufficient_funds: !quoteRequest.insufficientBal,
+          ...inputPrimaryDenominationProperties,
           ...baseProperties,
         };
       case UnifiedSwapBridgeEventName.QuotesError:
diff --git a/packages/bridge-controller/src/constants/bridge.ts b/packages/bridge-controller/src/constants/bridge.ts
index f123315cb4..79d35f0f3e 100644
--- a/packages/bridge-controller/src/constants/bridge.ts
+++ b/packages/bridge-controller/src/constants/bridge.ts
@@ -96,6 +96,7 @@ export const DEFAULT_BRIDGE_CONTROLLER_STATE: BridgeControllerState = {
   minimumBalanceForRentExemptionInLamports: '0',
   tokenWarnings: [],
   tokenSecurityTypeDestination: null,
+  inputPrimaryDenomination: 'token_amount',
   quoteStreamComplete: null,
   batchSellTrades: null,
   batchSellTradesLoadingStatus: null,
diff --git a/packages/bridge-controller/src/index.ts b/packages/bridge-controller/src/index.ts
index 88a9b994b6..b89fb5f7c0 100644
--- a/packages/bridge-controller/src/index.ts
+++ b/packages/bridge-controller/src/index.ts
@@ -18,6 +18,7 @@ export type {
   TxStatusData,
   QuoteFetchData,
   QuoteWarning,
+  InputPrimaryDenominationData,
 } from './utils/metrics/types';
 
 export {
@@ -55,6 +56,7 @@ export type {
   BitcoinTradeData,
   TronTradeData,
   BridgeControllerState,
+  InputPrimaryDenomination,
   BridgeControllerAction,
   BridgeControllerActions,
   BridgeControllerEvents,
@@ -68,6 +70,7 @@ export type {
   BridgeControllerFetchQuotesAction,
   BridgeControllerStopPollingForQuotesAction,
   BridgeControllerSetLocationAction,
+  BridgeControllerSetInputPrimaryDenominationAction,
   BridgeControllerResetStateAction,
   BridgeControllerSetChainIntervalLengthAction,
   BridgeControllerTrackUnifiedSwapBridgeEventAction,
diff --git a/packages/bridge-controller/src/types.ts b/packages/bridge-controller/src/types.ts
index 2d842012ca..c95a37e00c 100644
--- a/packages/bridge-controller/src/types.ts
+++ b/packages/bridge-controller/src/types.ts
@@ -87,6 +87,8 @@ export type NonEvmFees = {
   nonEvmFeesInNative?: string; // Non-EVM chain fees in native units (SOL for Solana, BTC for Bitcoin)
 };
 
+export type InputPrimaryDenomination = 'token_amount' | 'fiat_value';
+
 /**
  * The types of values for the token amount and its values when converted to the user's selected currency and USD
  */
@@ -434,6 +436,12 @@ export type BridgeControllerState = {
    * reset. `null` when the client has no security data for the token.
    */
   tokenSecurityTypeDestination: string | null;
+  /**
+   * The denomination currently shown as the primary source amount input.
+   * This is persisted as a user preference so returning to the flow restores
+   * the last selected fiat/token display mode.
+   */
+  inputPrimaryDenomination: InputPrimaryDenomination;
   /**
    * Metadata about the completed quote stream, populated from the `complete` SSE event.
    * Set to null at the start of each fetch and updated when the complete event is received.
diff --git a/packages/bridge-controller/src/utils/metrics/constants.ts b/packages/bridge-controller/src/utils/metrics/constants.ts
index 86c28f63be..63022cdc2b 100644
--- a/packages/bridge-controller/src/utils/metrics/constants.ts
+++ b/packages/bridge-controller/src/utils/metrics/constants.ts
@@ -8,6 +8,7 @@ export enum UnifiedSwapBridgeEventName {
   ButtonClicked = `${UNIFIED_SWAP_BRIDGE_EVENT_CATEGORY} Button Clicked`,
   PageViewed = `${UNIFIED_SWAP_BRIDGE_EVENT_CATEGORY} Page Viewed`,
   InputChanged = `${UNIFIED_SWAP_BRIDGE_EVENT_CATEGORY} Input Changed`,
+  FiatCryptoToggleClicked = `${UNIFIED_SWAP_BRIDGE_EVENT_CATEGORY} Fiat Crypto Toggle Clicked`,
   InputSourceDestinationSwitched = `${UNIFIED_SWAP_BRIDGE_EVENT_CATEGORY} Source Destination Switched`,
   QuotesRequested = `${UNIFIED_SWAP_BRIDGE_EVENT_CATEGORY} Quotes Requested`,
   QuotesReceived = `${UNIFIED_SWAP_BRIDGE_EVENT_CATEGORY} Quotes Received`,
diff --git a/packages/bridge-controller/src/utils/metrics/types.ts b/packages/bridge-controller/src/utils/metrics/types.ts
index 73382e442b..2052827aec 100644
--- a/packages/bridge-controller/src/utils/metrics/types.ts
+++ b/packages/bridge-controller/src/utils/metrics/types.ts
@@ -1,7 +1,12 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import type { CaipAssetType, CaipChainId } from '@metamask/utils';
 
-import type { FeatureId, SortOrder, StatusTypes } from '../../types';
+import type {
+  FeatureId,
+  InputPrimaryDenomination,
+  SortOrder,
+  StatusTypes,
+} from '../../types';
 import type {
   UnifiedSwapBridgeEventName,
   MetaMetricsSwapsEventSource,
@@ -74,6 +79,10 @@ export type TxStatusData = {
   destination_transaction?: StatusTypes;
 };
 
+export type InputPrimaryDenominationData = {
+  input_primary_denomination?: InputPrimaryDenomination;
+};
+
 export type InputKeys =
   | 'token_source'
   | 'token_destination'
@@ -125,6 +134,18 @@ type RequiredEventContextFromClientBase = {
     input_value: InputValues[keyof InputValues];
     input_amount_preset?: string;
   };
+  [UnifiedSwapBridgeEventName.FiatCryptoToggleClicked]: {
+    token_symbol_source: string;
+    token_symbol_destination: string | null;
+    previous_primary_denomination: InputPrimaryDenomination;
+    new_primary_denomination: InputPrimaryDenomination;
+    chain_id_source?: RequestParams['chain_id_source'];
+    chain_id_destination?: RequestParams['chain_id_destination'];
+    token_address_source?: RequestParams['token_address_source'];
+    token_address_destination?: RequestParams['token_address_destination'];
+    token_security_type_destination?: RequestParams['token_security_type_destination'];
+    swap_type?: RequestMetadata['swap_type'];
+  };
   [UnifiedSwapBridgeEventName.InputSourceDestinationSwitched]: {
     token_symbol_source: RequestParams['token_symbol_source'];
     token_symbol_destination: RequestParams['token_symbol_destination'];
@@ -141,9 +162,10 @@ type RequiredEventContextFromClientBase = {
     token_symbol_source: RequestParams['token_symbol_source'];
     token_symbol_destination: RequestParams['token_symbol_destination'];
     token_security_type_destination: RequestParams['token_security_type_destination'];
-  };
+  } & InputPrimaryDenominationData;
   [UnifiedSwapBridgeEventName.QuotesReceived]: TradeData &
-    Pick<RequestParams, 'token_symbol_source' | 'token_symbol_destination'> & {
+    Pick<RequestParams, 'token_symbol_source' | 'token_symbol_destination'> &
+    InputPrimaryDenominationData & {
       warnings: QuoteWarning[];
       best_quote_provider: QuoteFetchData['best_quote_provider'];
       price_impact: QuoteFetchData['price_impact'];
@@ -174,7 +196,7 @@ type RequiredEventContextFromClientBase = {
     > & {
       action_type: MetricsActionType;
       batch_id?: string;
-    };
+    } & InputPrimaryDenominationData;
   [UnifiedSwapBridgeEventName.Completed]: TradeData &
     Pick<QuoteFetchData, 'price_impact'> &
     Omit<RequestMetadata, 'security_warnings'> &
@@ -187,7 +209,7 @@ type RequiredEventContextFromClientBase = {
       quoted_vs_used_gas_ratio: number;
       action_type: MetricsActionType;
       batch_id?: string;
-    };
+    } & InputPrimaryDenominationData;
   [UnifiedSwapBridgeEventName.Failed]: (
     | // Tx failed before confirmation
       (Pick<
@@ -224,7 +246,7 @@ type RequiredEventContextFromClientBase = {
   [UnifiedSwapBridgeEventName.StatusValidationFailed]: {
     failures: string[];
     refresh_count: number;
-  };
+  } & Partial<RequestParams>;
   // Emitted by clients
   [UnifiedSwapBridgeEventName.AllQuotesOpened]: Pick<
     TradeData,
@@ -294,22 +316,25 @@ export type EventPropertiesFromControllerState = {
     Omit<
       RequestMetadata,
       'stx_enabled' | 'usd_amount_source' | 'security_warnings'
-    >;
+    > &
+    InputPrimaryDenominationData;
   [UnifiedSwapBridgeEventName.InputChanged]: {
     input: InputKeys;
     input_value: string;
   };
+  [UnifiedSwapBridgeEventName.FiatCryptoToggleClicked]: RequestParams &
+    Pick<RequestMetadata, 'swap_type'>;
   [UnifiedSwapBridgeEventName.InputSourceDestinationSwitched]: RequestParams;
   [UnifiedSwapBridgeEventName.QuotesRequested]: RequestParams &
     RequestMetadata & {
       has_sufficient_funds: boolean;
-    };
+    } & InputPrimaryDenominationData;
   [UnifiedSwapBridgeEventName.QuotesReceived]: RequestParams &
     RequestMetadata &
     QuoteFetchData &
     TradeData & {
       refresh_count: number; // starts from 0
-    };
+    } & InputPrimaryDenominationData;
   [UnifiedSwapBridgeEventName.QuotesError]: RequestParams &
     RequestMetadata & {
       has_sufficient_funds: boolean;
diff --git a/packages/bridge-status-controller/CHANGELOG.md b/packages/bridge-status-controller/CHANGELOG.md
index 3ee7de6c1e..45028e8104 100644
--- a/packages/bridge-status-controller/CHANGELOG.md
+++ b/packages/bridge-status-controller/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add input primary denomination to submitted bridge history and post-submit analytics ([#9147](https://github.com/MetaMask/core/pull/9147))
+
 ## [72.1.1]
 
 ### Changed
diff --git a/packages/bridge-status-controller/src/bridge-status-controller.ts b/packages/bridge-status-controller/src/bridge-status-controller.ts
index 4469adae67..a1e1b1adb9 100644
--- a/packages/bridge-status-controller/src/bridge-status-controller.ts
+++ b/packages/bridge-status-controller/src/bridge-status-controller.ts
@@ -6,6 +6,7 @@ import {
   Trade,
   FeatureId,
   BatchSellTradesResponse,
+  InputPrimaryDenomination,
 } from '@metamask/bridge-controller';
 import {
   isNonEvmChainId,
@@ -949,6 +950,7 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
       abTests?: Record<string, string>;
       activeAbTests?: { key: string; value: string }[];
       tokenSecurityTypeDestination?: string | null;
+      inputPrimaryDenomination?: InputPrimaryDenomination;
     },
   ): Promise<TransactionMeta> => {
     let tradeTxMeta!: TransactionMeta;
@@ -1028,6 +1030,7 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
    * @param activeAbTests - New A/B test context for `active_ab_tests` (migration target). Attributes events to specific experiments.
    * @param tokenSecurityTypeDestination - The security classification of the destination token, supplied by the client (e.g. from token security/scanning data). Pass `null` when no security data is available.
    * @param batchSellTrades - Contains transaction data for the quotes, provided by the obtainGaslessBatch API
+   * @param inputPrimaryDenomination - The denomination shown as the primary source amount input at submission time.
    * @returns The transaction meta
    * @throws An error if transaction submission fails before it gets published
    */
@@ -1043,6 +1046,7 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
     activeAbTests?: { key: string; value: string }[],
     tokenSecurityTypeDestination?: string | null,
     batchSellTrades?: BatchSellTradesResponse | null,
+    inputPrimaryDenomination?: InputPrimaryDenomination,
   ): Promise<TransactionMeta> => {
     /**
      * If there are multiple quote responses, we assume that they all originate from the same src chain
@@ -1099,7 +1103,12 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
       this.#trackUnifiedSwapBridgeEvent(
         UnifiedSwapBridgeEventName.Submitted,
         undefined,
-        preConfirmationProperties,
+        {
+          ...preConfirmationProperties,
+          ...(inputPrimaryDenomination && {
+            input_primary_denomination: inputPrimaryDenomination,
+          }),
+        },
       );
 
       /**
@@ -1141,6 +1150,7 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
             abTests,
             activeAbTests,
             tokenSecurityTypeDestination,
+            inputPrimaryDenomination,
           }),
       );
     } catch (error) {
@@ -1167,6 +1177,7 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
    * @param params.abTests - Legacy A/B test context for `ab_tests` (backward compatibility)
    * @param params.activeAbTests - New A/B test context for `active_ab_tests` (migration target). Attributes events to specific experiments.
    * @param params.tokenSecurityTypeDestination - The security classification of the destination token, supplied by the client (e.g. from token security/scanning data). Pass `null` when no security data is available.
+   * @param params.inputPrimaryDenomination - The denomination shown as the primary source amount input at submission time.
    * @param params.isStxEnabled - Whether smart transactions are enabled on the client, for example the getSmartTransactionsEnabled selector value from the extension
    * @param params.quotesReceivedContext - The context for the QuotesReceived event
    * @returns A lightweight TransactionMeta-like object for history linking
@@ -1179,6 +1190,7 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
     abTests?: Record<string, string>;
     activeAbTests?: { key: string; value: string }[];
     tokenSecurityTypeDestination?: string | null;
+    inputPrimaryDenomination?: InputPrimaryDenomination;
     isStxEnabled?: boolean;
     quotesReceivedContext?: RequiredEventContextFromClient[UnifiedSwapBridgeEventName.QuotesReceived];
   }): Promise<TransactionMeta> => {
@@ -1189,6 +1201,7 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
       abTests,
       activeAbTests,
       tokenSecurityTypeDestination,
+      inputPrimaryDenomination,
       isStxEnabled = false,
       quotesReceivedContext,
     } = params;
@@ -1203,6 +1216,8 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
       abTests,
       activeAbTests,
       tokenSecurityTypeDestination,
+      undefined,
+      inputPrimaryDenomination,
     );
   };
 
@@ -1384,6 +1399,10 @@ export class BridgeStatusController extends StaticIntervalPollingController<Brid
       ...getTxStatusesFromHistory(historyItem),
       ...getFinalizedTxProperties(historyItem, txMeta, approvalTxMeta),
       ...getPriceImpactFromQuote(quote),
+      ...(eventName === UnifiedSwapBridgeEventName.Completed &&
+        historyItem.inputPrimaryDenomination && {
+          input_primary_denomination: historyItem.inputPrimaryDenomination,
+        }),
     };
 
     trackMetricsEvent({
diff --git a/packages/bridge-status-controller/src/types.ts b/packages/bridge-status-controller/src/types.ts
index 16763b1638..ee68774781 100644
--- a/packages/bridge-status-controller/src/types.ts
+++ b/packages/bridge-status-controller/src/types.ts
@@ -17,6 +17,7 @@ import type {
   BridgeControllerStopPollingForQuotesAction,
   BatchSellTradesResponse,
   BridgeControllerGetStateAction,
+  InputPrimaryDenomination,
 } from '@metamask/bridge-controller';
 import type { KeyringControllerSignTypedMessageAction } from '@metamask/keyring-controller';
 import type { Messenger } from '@metamask/messenger';
@@ -208,6 +209,11 @@ export type BridgeHistoryItem = {
    * available for the destination token.
    */
   tokenSecurityTypeDestination?: string | null;
+  /**
+   * The denomination shown as the primary source amount input when the
+   * swap/bridge was submitted.
+   */
+  inputPrimaryDenomination?: InputPrimaryDenomination;
 };
 
 /**
@@ -287,6 +293,8 @@ export type StartPollingForBridgeTxStatusArgs = {
   // Client-supplied destination token security classification, persisted on
   // the history item for post-submit analytics events.
   tokenSecurityTypeDestination?: BridgeHistoryItem['tokenSecurityTypeDestination'];
+  // Primary denomination at submission time, persisted for post-submit analytics.
+  inputPrimaryDenomination?: BridgeHistoryItem['inputPrimaryDenomination'];
 };
 
 /**
diff --git a/packages/bridge-status-controller/src/utils/history.test.ts b/packages/bridge-status-controller/src/utils/history.test.ts
index 04f522c706..695e9d4ab3 100644
--- a/packages/bridge-status-controller/src/utils/history.test.ts
+++ b/packages/bridge-status-controller/src/utils/history.test.ts
@@ -152,5 +152,13 @@ describe('History Utils', () => {
       });
       expect(txHistoryItem.tokenSecurityTypeDestination).toBeNull();
     });
+
+    it('persists inputPrimaryDenomination when provided', () => {
+      const txHistoryItem = getInitialHistoryItem({
+        ...baseArgs,
+        inputPrimaryDenomination: 'fiat_value',
+      });
+      expect(txHistoryItem.inputPrimaryDenomination).toBe('fiat_value');
+    });
   });
 });
diff --git a/packages/bridge-status-controller/src/utils/history.ts b/packages/bridge-status-controller/src/utils/history.ts
index f44092d7e1..4c20f2134a 100644
--- a/packages/bridge-status-controller/src/utils/history.ts
+++ b/packages/bridge-status-controller/src/utils/history.ts
@@ -206,6 +206,7 @@ export const getInitialHistoryItem = (
     originalTransactionId,
     actionId,
     tokenSecurityTypeDestination,
+    inputPrimaryDenomination,
     batchSellData,
     quoteIds,
   } = args;
@@ -256,6 +257,9 @@ export const getInitialHistoryItem = (
     ...(tokenSecurityTypeDestination !== undefined && {
       tokenSecurityTypeDestination,
     }),
+    ...(inputPrimaryDenomination !== undefined && {
+      inputPrimaryDenomination,
+    }),
   };
 
   if (batchSellData) {