diff --git a/moto/awslambda/models.py b/moto/awslambda/models.py
index 38ff81fb2..e43f8e5d0 100644
--- a/moto/awslambda/models.py
+++ b/moto/awslambda/models.py
@@ -409,6 +409,7 @@ class LambdaFunction(BaseModel):
                         volumes=["{}:/var/task".format(data_vol.name)],
                         environment=env_vars,
                         detach=True,
+                        log_config=docker.types.LogConfig(type=docker.types.LogConfig.types.JSON),
                         **run_kwargs
                     )
                 finally: