diff --git a/templates/tools/dockerfile/python_build_interop.sh.include b/templates/tools/dockerfile/python_build_interop.sh.include
index 56b9af50a79..4b3503a1cd4 100644
--- a/templates/tools/dockerfile/python_build_interop.sh.include
+++ b/templates/tools/dockerfile/python_build_interop.sh.include
@@ -28,4 +28,5 @@ cp -r /var/local/jenkins/service_account $HOME || true
 
 cd /var/local/git/grpc
 
-tools/run_tests/run_tests.py -l python --compiler python3 -c opt --build_only
+# interop tests only run using python3.9 currently (and python build is slow)
+tools/run_tests/run_tests.py -l python --compiler python3.9 -c opt --build_only
diff --git a/tools/dockerfile/interoptest/grpc_interop_python/build_interop.sh b/tools/dockerfile/interoptest/grpc_interop_python/build_interop.sh
index 5bb3e292f78..c6818285b57 100755
--- a/tools/dockerfile/interoptest/grpc_interop_python/build_interop.sh
+++ b/tools/dockerfile/interoptest/grpc_interop_python/build_interop.sh
@@ -28,4 +28,5 @@ cp -r /var/local/jenkins/service_account $HOME || true
 
 cd /var/local/git/grpc
 
-tools/run_tests/run_tests.py -l python --compiler python3 -c opt --build_only
+# interop tests only run using python3.9 currently (and python build is slow)
+tools/run_tests/run_tests.py -l python --compiler python3.9 -c opt --build_only
diff --git a/tools/dockerfile/interoptest/grpc_interop_pythonasyncio/build_interop.sh b/tools/dockerfile/interoptest/grpc_interop_pythonasyncio/build_interop.sh
index 5bb3e292f78..c6818285b57 100755
--- a/tools/dockerfile/interoptest/grpc_interop_pythonasyncio/build_interop.sh
+++ b/tools/dockerfile/interoptest/grpc_interop_pythonasyncio/build_interop.sh
@@ -28,4 +28,5 @@ cp -r /var/local/jenkins/service_account $HOME || true
 
 cd /var/local/git/grpc
 
-tools/run_tests/run_tests.py -l python --compiler python3 -c opt --build_only
+# interop tests only run using python3.9 currently (and python build is slow)
+tools/run_tests/run_tests.py -l python --compiler python3.9 -c opt --build_only