diff --git a/CHANGELOG.md b/CHANGELOG.md
index 79afc9a..36f693f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](http://semver.org/) and [Keep a Ch
 
 ### Fixes
 - Adds validation for trusted principal arns in `seedfarmer bootstrap toolchain`
+- Add region to sts boto client if using aws-cn partition
 
 ## v4.0.4 (2024-07-19)
 
diff --git a/seedfarmer/services/session_manager.py b/seedfarmer/services/session_manager.py
index 6318790..91d8d10 100644
--- a/seedfarmer/services/session_manager.py
+++ b/seedfarmer/services/session_manager.py
@@ -149,6 +149,7 @@ def get_deployment_session(self, account_id: str, region_name: str) -> Session:
                 aws_access_key_id=toolchain_role["Credentials"]["AccessKeyId"],
                 aws_secret_access_key=toolchain_role["Credentials"]["SecretAccessKey"],
                 aws_session_token=toolchain_role["Credentials"]["SessionToken"],
+                region_name=region_name if region_name in ["cn-north-1", "cn-northwest-1"] else None,
             )
             partition = sts_toolchain_client.get_caller_identity().get("Arn").split(":")[1]
             deployment_role_arn = get_deployment_role_arn(