diff --git a/packages/google-cloud-testutils/mypy.ini b/packages/google-cloud-testutils/mypy.ini
index 8efb6f7241c8..569486a9ce60 100644
--- a/packages/google-cloud-testutils/mypy.ini
+++ b/packages/google-cloud-testutils/mypy.ini
@@ -1,3 +1,3 @@
 [mypy]
-python_version = 3.9
+python_version = 3.10
 exclude = tests/unit/resources/
diff --git a/packages/google-cloud-testutils/noxfile.py b/packages/google-cloud-testutils/noxfile.py
index 65f9c1ee1967..7dc4933e82bb 100644
--- a/packages/google-cloud-testutils/noxfile.py
+++ b/packages/google-cloud-testutils/noxfile.py
@@ -32,7 +32,7 @@
 # Error if a python version is missing
 nox.options.error_on_missing_interpreters = True
 
-ALL_PYTHON = ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
+ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14"]
 DEFAULT_PYTHON_VERSION = "3.14"
 BLACK_VERSION = "black==23.7.0"
 BLACK_PATHS = ["test_utils", "setup.py"]
@@ -128,7 +128,7 @@ def system(session):
         "--package-name",
         "google-cloud-testutils",
         "--constraints-file",
-        "testing/constraints-3.9.txt",
+        "testing/constraints-3.10.txt",
     )
 
 
@@ -142,7 +142,7 @@ def update_lower_bounds(session):
         "--package-name",
         "google-cloud-testutils",
         "--constraints-file",
-        "testing/constraints-3.9.txt",
+        "testing/constraints-3.10.txt",
     )
 
 
diff --git a/packages/google-cloud-testutils/setup.py b/packages/google-cloud-testutils/setup.py
index bdfa71c0d3ef..89e592a34965 100644
--- a/packages/google-cloud-testutils/setup.py
+++ b/packages/google-cloud-testutils/setup.py
@@ -55,17 +55,16 @@
     platforms="Posix; MacOS X; Windows",
     include_package_data=True,
     install_requires=(
-        "google-auth >= 0.4.0",
+        "google-auth >= 2.1.0",
         "click>=7.0.0",
         "packaging>=22.0",
     ),
-    python_requires=">=3.9",
+    python_requires=">=3.10",
     classifiers=[
         "Development Status :: 4 - Beta",
         "Intended Audience :: Developers",
         "Operating System :: OS Independent",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: 3.12",
diff --git a/packages/google-cloud-testutils/testing/constraints-3.10.txt b/packages/google-cloud-testutils/testing/constraints-3.10.txt
index e69de29bb2d1..91463bdd5b6e 100644
--- a/packages/google-cloud-testutils/testing/constraints-3.10.txt
+++ b/packages/google-cloud-testutils/testing/constraints-3.10.txt
@@ -0,0 +1,10 @@
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List *all* library dependencies and extras in this file.
+# Pin the version to the lower bound.
+#
+# e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
+# Then this file should have foo==1.14.0
+click==7.0.0
+google-auth==2.1.0
+packaging==22.0
diff --git a/packages/google-cloud-testutils/testing/constraints-3.9.txt b/packages/google-cloud-testutils/testing/constraints-3.9.txt
deleted file mode 100644
index 98913de3c413..000000000000
--- a/packages/google-cloud-testutils/testing/constraints-3.9.txt
+++ /dev/null
@@ -1,10 +0,0 @@
-# This constraints file is used to check that lower bounds
-# are correct in setup.py
-# List *all* library dependencies and extras in this file.
-# Pin the version to the lower bound.
-#
-# e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
-# Then this file should have foo==1.14.0
-click==7.0.0
-google-auth==0.4.0
-packaging==22.0
diff --git a/packages/google-cloud-testutils/tests/unit/resources/bad_package/setup.py b/packages/google-cloud-testutils/tests/unit/resources/bad_package/setup.py
index a26333eace12..dd2897f2502a 100644
--- a/packages/google-cloud-testutils/tests/unit/resources/bad_package/setup.py
+++ b/packages/google-cloud-testutils/tests/unit/resources/bad_package/setup.py
@@ -36,5 +36,5 @@
     ],
     install_requires=requirements,
     packages=setuptools.find_packages(),
-    python_requires=">=3.9",
+    python_requires=">=3.9",  # version-scanner: ignore
 )
diff --git a/packages/google-cloud-testutils/tests/unit/resources/good_package/setup.py b/packages/google-cloud-testutils/tests/unit/resources/good_package/setup.py
index 85e83788cd9c..6bca9f026b15 100644
--- a/packages/google-cloud-testutils/tests/unit/resources/good_package/setup.py
+++ b/packages/google-cloud-testutils/tests/unit/resources/good_package/setup.py
@@ -42,5 +42,5 @@
     install_requires=requirements,
     extras_require=extras,
     packages=setuptools.find_packages(),
-    python_requires=">=3.9",
+    python_requires=">=3.9",  # version-scanner: ignore
 )