diff --git a/.changeset/forty-cooks-deny.md b/.changeset/forty-cooks-deny.md
new file mode 100644
index 00000000000..315ad073cfb
--- /dev/null
+++ b/.changeset/forty-cooks-deny.md
@@ -0,0 +1,5 @@
+---
+"@smithy/types": patch
+---
+
+add interface stub for browser RequestInit type
diff --git a/packages/types/src/http/httpHandlerInitialization.ts b/packages/types/src/http/httpHandlerInitialization.ts
index 4bc56843c62..a81aa50dd10 100644
--- a/packages/types/src/http/httpHandlerInitialization.ts
+++ b/packages/types/src/http/httpHandlerInitialization.ts
@@ -125,3 +125,10 @@ export interface FetchHttpHandlerOptions {
    */
   requestInit?: (httpRequest: IHttpRequest) => RequestInit;
 }
+
+declare global {
+  /**
+   * interface merging stub.
+   */
+  interface RequestInit {}
+}