diff --git a/.changeset/gold-rooms-bake.md b/.changeset/gold-rooms-bake.md
new file mode 100644
index 00000000000..1bc2ffe73d6
--- /dev/null
+++ b/.changeset/gold-rooms-bake.md
@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+Banner: stack inline actions vertically on narrow viewports.
diff --git a/packages/react/src/Banner/Banner.module.css b/packages/react/src/Banner/Banner.module.css
index 07b04346567..ce747ade8bc 100644
--- a/packages/react/src/Banner/Banner.module.css
+++ b/packages/react/src/Banner/Banner.module.css
@@ -40,6 +40,10 @@
 
     & .BannerActions :where([data-primary-action='trailing']) {
       display: flex;
+
+      @media screen and (--viewportRange-narrow) {
+        flex-direction: column;
+      }
     }
 
     & .BannerActions :where([data-primary-action='leading']) {