diff --git a/packages/gatsby-plugin-sitemap/src/__tests__/gatsby-node.js b/packages/gatsby-plugin-sitemap/src/__tests__/gatsby-node.js
index 44f11c269e478..712cb8f4fcfce 100644
--- a/packages/gatsby-plugin-sitemap/src/__tests__/gatsby-node.js
+++ b/packages/gatsby-plugin-sitemap/src/__tests__/gatsby-node.js
@@ -19,6 +19,12 @@ const reporter = {
   panic: jest.fn(),
 }
 
+const mockStoreGetState = jest.fn(() => ({config: {}}))
+
+const store = {
+  getState: mockStoreGetState
+}
+
 beforeEach(() => {
   global.__PATH_PREFIX__ = ``
 
@@ -48,7 +54,7 @@ describe(`gatsby-plugin-sitemap Node API`, () => {
       },
     })
     await onPostBuild(
-      { graphql, pathPrefix, reporter },
+      { graphql, pathPrefix, reporter, store },
       await schema.validateAsync({})
     )
     const {
@@ -106,7 +112,7 @@ describe(`gatsby-plugin-sitemap Node API`, () => {
     }
 
     await onPostBuild(
-      { graphql, pathPrefix, reporter },
+      { graphql, pathPrefix, reporter, store },
       await schema.validateAsync(options)
     )
 
@@ -147,7 +153,7 @@ describe(`gatsby-plugin-sitemap Node API`, () => {
     }
     const prefix = `/test`
     await onPostBuild(
-      { graphql, pathPrefix: prefix, reporter },
+      { graphql, pathPrefix: prefix, reporter, store },
       await schema.validateAsync(options)
     )
     const { sourceData } = sitemap.simpleSitemapAndIndex.mock.calls[0][0]
@@ -182,8 +188,15 @@ describe(`gatsby-plugin-sitemap Node API`, () => {
     const options = {
       output: subdir,
     }
+
+    mockStoreGetState.mockImplementationOnce(() => ({
+      config: {
+        assetPrefix: 'assets'
+      }
+    }))
+
     await onPostBuild(
-      { graphql, pathPrefix: prefix, reporter },
+      { graphql, pathPrefix: prefix, reporter, store },
       await schema.validateAsync(options)
     )
     expect(sitemap.simpleSitemapAndIndex.mock.calls[0][0].publicBasePath).toBe(
diff --git a/packages/gatsby-plugin-sitemap/src/__tests__/internals.js b/packages/gatsby-plugin-sitemap/src/__tests__/internals.js
index ad125320717a6..26f326a43d680 100644
--- a/packages/gatsby-plugin-sitemap/src/__tests__/internals.js
+++ b/packages/gatsby-plugin-sitemap/src/__tests__/internals.js
@@ -27,14 +27,31 @@ describe(`gatsby-plugin-sitemap internals tests`, () => {
     expect(result2).toStrictEqual(`/test/path`)
   })
 
-  it(`prefixPath should correctly concatonate path`, () => {
-    const result = prefixPath({
+  it(`prefixPath should correctly concatenate path`, () => {
+    const resultIfPathPrefix = prefixPath({
       url: TestPath,
       siteUrl: SiteUrl,
       pathPrefix: `/root`,
     })
 
-    expect(result).toStrictEqual(`https://example.net/root/test/path/`)
+    expect(resultIfPathPrefix).toStrictEqual(`https://example.net/root/test/path/`)
+
+    const resultIfAssetPrefix = prefixPath({
+      url: TestPath,
+      siteUrl: SiteUrl,
+      assetPrefix: 'assets'
+    })
+
+    expect(resultIfAssetPrefix).toStrictEqual(`https://example.net/test/path/`)
+
+    const resultIfAssetAndPathPrefix = prefixPath({
+      url: TestPath,
+      siteUrl: SiteUrl,
+      pathPrefix: `/assets/root`,
+      assetPrefix: 'assets'
+    })
+
+    expect(resultIfAssetAndPathPrefix).toStrictEqual(`https://example.net/root/test/path/`)
   })
 
   it(`resolveSiteUrl should return SiteUrl`, () => {
diff --git a/packages/gatsby-plugin-sitemap/src/gatsby-node.js b/packages/gatsby-plugin-sitemap/src/gatsby-node.js
index 0021f33b17449..a0bca9ba2ab0f 100644
--- a/packages/gatsby-plugin-sitemap/src/gatsby-node.js
+++ b/packages/gatsby-plugin-sitemap/src/gatsby-node.js
@@ -6,7 +6,7 @@ import { prefixPath, pageFilter, REPORTER_PREFIX } from "./internals"
 exports.pluginOptionsSchema = pluginOptionsSchema
 
 exports.onPostBuild = async (
-  { graphql, reporter, pathPrefix },
+  { graphql, reporter, pathPrefix, store },
   {
     output,
     entryLimit,
@@ -66,6 +66,10 @@ exports.onPostBuild = async (
     `${REPORTER_PREFIX} ${filteredPages.length} pages remain after filtering`
   )
 
+  const { assetPrefix } = store.getState().config
+
+  
+
   const serializedPages = []
 
   for (const page of filteredPages) {
@@ -74,7 +78,7 @@ exports.onPostBuild = async (
         serialize(page, { resolvePagePath })
       )
       serializedPages.push({
-        url: prefixPath({ url, siteUrl, pathPrefix }),
+        url: prefixPath({ url, siteUrl, pathPrefix, assetPrefix }),
         ...rest,
       })
     } catch (err) {
diff --git a/packages/gatsby-plugin-sitemap/src/internals.js b/packages/gatsby-plugin-sitemap/src/internals.js
index 255e25a8c303b..80e913e04ee63 100644
--- a/packages/gatsby-plugin-sitemap/src/internals.js
+++ b/packages/gatsby-plugin-sitemap/src/internals.js
@@ -19,9 +19,9 @@ export const withoutTrailingSlash = path =>
  * @param {string} siteUrl - results of the resolveSiteUrl function
  * @returns {string}
  */
-// TODO: Update for v3 - Fix janky path/asset prefixing
-export function prefixPath({ url, siteUrl, pathPrefix = `` }) {
-  return new URL(pathPrefix + url, siteUrl).toString()
+export function prefixPath({ url, siteUrl, pathPrefix = ``, assetPrefix }) {
+  const purePathPrefix = !assetPrefix ? pathPrefix : pathPrefix.replace(`/${assetPrefix}`, '')
+  return new URL(purePathPrefix + url, siteUrl).toString()
 }
 
 /**