diff --git a/mcpgateway/admin.py b/mcpgateway/admin.py
index c513761494..dc07b20693 100644
--- a/mcpgateway/admin.py
+++ b/mcpgateway/admin.py
@@ -12339,15 +12339,16 @@ async def admin_edit_gateway(
                 auth_headers = []
 
         # Handle passthrough_headers
-        passthrough_headers = str(form.get("passthrough_headers"))
-        if passthrough_headers and passthrough_headers.strip():
+        # Use [] (empty list) to signal "user cleared the field" vs None (not provided)
+        passthrough_headers_raw = form.get("passthrough_headers")
+        passthrough_headers_str = str(passthrough_headers_raw) if passthrough_headers_raw else ""
+        passthrough_headers: Optional[List[str]] = []
+        if passthrough_headers_str.strip():
             try:
-                passthrough_headers = orjson.loads(passthrough_headers)
+                passthrough_headers = orjson.loads(passthrough_headers_str)
             except (orjson.JSONDecodeError, ValueError):
                 # Fallback to comma-separated parsing
-                passthrough_headers = [h.strip() for h in passthrough_headers.split(",") if h.strip()]
-        else:
-            passthrough_headers = None
+                passthrough_headers = [h.strip() for h in passthrough_headers_str.split(",") if h.strip()]
 
         # Parse OAuth configuration - support both JSON string and individual form fields
         oauth_config_json = str(form.get("oauth_config"))
diff --git a/mcpgateway/services/gateway_service.py b/mcpgateway/services/gateway_service.py
index 90c488e385..f18c7a922b 100644
--- a/mcpgateway/services/gateway_service.py
+++ b/mcpgateway/services/gateway_service.py
@@ -2144,11 +2144,12 @@ async def update_gateway(
                             prompt.visibility = gateway.visibility
                 if gateway_update.passthrough_headers is not None:
                     if isinstance(gateway_update.passthrough_headers, list):
-                        gateway.passthrough_headers = gateway_update.passthrough_headers
+                        # [] means "user cleared the field" → store None in DB
+                        gateway.passthrough_headers = gateway_update.passthrough_headers if gateway_update.passthrough_headers else None
                     else:
                         if isinstance(gateway_update.passthrough_headers, str):
                             parsed: List[str] = [h.strip() for h in gateway_update.passthrough_headers.split(",") if h.strip()]
-                            gateway.passthrough_headers = parsed
+                            gateway.passthrough_headers = parsed if parsed else None
                         else:
                             raise GatewayError("Invalid passthrough_headers format: must be list[str] or comma-separated string")