diff --git a/esphome/components/api/user_services.h b/esphome/components/api/user_services.h
index 85fba2a435..0fc529108c 100644
--- a/esphome/components/api/user_services.h
+++ b/esphome/components/api/user_services.h
@@ -264,9 +264,9 @@ template<typename... Ts> class APIRespondAction : public Action<Ts...> {
       // Build and send JSON response
       json::JsonBuilder builder;
       this->json_builder_(x..., builder.root());
-      std::string json_str = builder.serialize();
+      auto json_buf = builder.serialize();
       this->parent_->send_action_response(call_id, success, StringRef(error_message),
-                                          reinterpret_cast<const uint8_t *>(json_str.data()), json_str.size());
+                                          reinterpret_cast<const uint8_t *>(json_buf.data()), json_buf.size());
       return;
     }
 #endif