diff --git a/tools/azure-sdk-tools/devtools_testutils/proxy_fixtures.py b/tools/azure-sdk-tools/devtools_testutils/proxy_fixtures.py
index c6733be223f8..2d553c646544 100644
--- a/tools/azure-sdk-tools/devtools_testutils/proxy_fixtures.py
+++ b/tools/azure-sdk-tools/devtools_testutils/proxy_fixtures.py
@@ -94,10 +94,13 @@ def get_or_record(self, variable: str, default: str) -> str:
         return self.variables.setdefault(variable, default)
 
 
-@pytest.fixture
+@pytest.fixture(scope="session")
 def environment_variables(test_proxy: None) -> EnvironmentVariableSanitizer:
     """Fixture that returns an EnvironmentVariableSanitizer for convenient environment variable fetching and sanitizing.
 
+    This fixture is session-scoped, so a single instance of EnvironmentVariableSanitizer is shared across all
+    tests using this fixture in the test session.
+
     :param test_proxy: The fixture responsible for starting up the test proxy server.
     :type test_proxy: None