diff --git a/docs/docs/reference/functions/getting-started.md b/docs/docs/reference/functions/getting-started.md
index 9051f6222126b..11af1364185b3 100644
--- a/docs/docs/reference/functions/getting-started.md
+++ b/docs/docs/reference/functions/getting-started.md
@@ -48,11 +48,15 @@ Functions can be written in JavaScript or Typescript.
 ```ts:title=src/api/typescript.ts
 import { GatsbyFunctionRequest, GatsbyFunctionResponse } from "gatsby"
 
+interface ContactBody {
+  message: string
+}
+
 export default function handler(
-  req: GatsbyFunctionRequest,
+  req: GatsbyFunctionRequest<ContactBody>,
   res: GatsbyFunctionResponse
 ) {
-  res.send(`I am TYPESCRIPT`)
+  res.send({ title: `I am TYPESCRIPT`, message: req.body.message })
 }
 ```
 
diff --git a/packages/gatsby/index.d.ts b/packages/gatsby/index.d.ts
index dc9b48971ac09..a4ad27b79b5cb 100644
--- a/packages/gatsby/index.d.ts
+++ b/packages/gatsby/index.d.ts
@@ -1648,7 +1648,7 @@ export interface GatsbyFunctionResponse<T = any> extends ServerResponse {
 /**
  * Gatsby function route request
  */
-export interface GatsbyFunctionRequest extends IncomingMessage {
+export interface GatsbyFunctionRequest<ReqBody = any> extends IncomingMessage {
   /**
    * Object of values from URL query parameters (after the ? in the URL)
    */
@@ -1658,7 +1658,7 @@ export interface GatsbyFunctionRequest extends IncomingMessage {
    * Object of values from route parameters
    */
   params: Record<string, string>
-  body: any
+  body: ReqBody
   /**
    * Object of `cookies` from header
    */