diff --git a/samcli/lib/build/app_builder.py b/samcli/lib/build/app_builder.py
index ed1ede172e..a01f164872 100644
--- a/samcli/lib/build/app_builder.py
+++ b/samcli/lib/build/app_builder.py
@@ -422,7 +422,8 @@ def _build_lambda_image(self, function_name: str, metadata: Dict, architecture:
         docker_context = cast(str, metadata.get("DockerContext"))
         # Have a default tag if not present.
         tag = metadata.get("DockerTag", "latest")
-        docker_tag = f"{function_name.lower()}:{tag}"
+        image_name = cast(str, metadata.get("DockerImage", function_name.lower()))
+        docker_tag = f"{image_name}:{tag}"
         docker_build_target = metadata.get("DockerBuildTarget", None)
         docker_build_args = metadata.get("DockerBuildArgs", {})