diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7cdbbac7c2..d57a37a33c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,12 @@
   - The default for creating views from templates will be .html, but .njk will be used if the app/config.json contains `"useNjkExtensions": true`.
   - If two views are in the same location with the same name but with different suffixes (html or njk), the default suffix (determined by the existence of the useNjkExtensions setting above) will be matched first followed by the alternative.
 
+### Fixes
+
+- [#2050: Update extends unbranded correctly during migrate](https://github.com/alphagov/govuk-prototype-kit/pull/2050)  
+  All occurences of "layout_unbranded.html" within the nunjucks files in the users app folder will be replaced with "govuk-prototype-kit/layouts/unbranded.html" during the migration process.
+
+
 ## 13.4.0
 
 ### New features
diff --git a/__tests__/fixtures/test-v11-prototype/app/views/nested-test-folder/unbranded-test.html b/__tests__/fixtures/test-v11-prototype/app/views/nested-test-folder/unbranded-test.html
new file mode 100644
index 0000000000..694912ebaf
--- /dev/null
+++ b/__tests__/fixtures/test-v11-prototype/app/views/nested-test-folder/unbranded-test.html
@@ -0,0 +1,6 @@
+{% extends "layout_unbranded.html" %}
+{% block pageScripts %}
+  <script>
+    console.log('Hello Unbranded')
+  </script>
+{% endblock %}
\ No newline at end of file
diff --git a/__tests__/spec/migrate.js b/__tests__/spec/migrate.js
index 7b85170fa2..d99b84c166 100644
--- a/__tests__/spec/migrate.js
+++ b/__tests__/spec/migrate.js
@@ -155,6 +155,19 @@ describe('migrate test prototype', () => {
     )
   })
 
+  it('unbranded-test.html should replace unbranded extend', () => {
+    const unbrandedFileContents = getNormalisedFileContent(path.join(appDirectory, 'views', 'nested-test-folder', 'unbranded-test.html'))
+
+    expect(unbrandedFileContents).toEqual(
+      '{% extends "govuk-prototype-kit/layouts/unbranded.html" %}\n' +
+      '{% block pageScripts %}\n' +
+      '  <script>\n' +
+      '    console.log(\'Hello Unbranded\')\n' +
+      '  </script>\n' +
+      '{% endblock %}'
+    )
+  })
+
   it('migrate.log does not contain user home directory', () => {
     const migrateLog = getNormalisedFileContent(path.join(projectDirectory, 'migrate.log'))
 
diff --git a/lib/utils/index.js b/lib/utils/index.js
index 74e8e6242e..9f7fc49549 100644
--- a/lib/utils/index.js
+++ b/lib/utils/index.js
@@ -2,6 +2,7 @@
 // core dependencies
 const crypto = require('crypto')
 const fs = require('fs')
+const fsp = fs.promises
 const https = require('https')
 const path = require('path')
 const { existsSync } = require('fs')
@@ -255,6 +256,27 @@ function recursiveDirectoryContentsSync (baseDir) {
   return goThroughDir()
 }
 
+async function searchAndReplaceFiles (dir, searchText, replaceText, extensions) {
+  const files = await fsp.readdir(dir)
+  const modifiedFiles = await Promise.all(files.map(async file => {
+    const filePath = path.join(dir, file)
+    const fileStat = await fsp.stat(filePath)
+
+    if (fileStat.isDirectory()) {
+      return await searchAndReplaceFiles(filePath, searchText, replaceText, extensions)
+    } else if (extensions.some(extension => file.endsWith(extension))) {
+      let fileContent = await fsp.readFile(filePath, 'utf8')
+      if (fileContent.includes(searchText)) {
+        fileContent = fileContent.replace(new RegExp(searchText, 'g'), replaceText)
+        await fsp.writeFile(filePath, fileContent)
+        return filePath
+      }
+    }
+  }))
+
+  return modifiedFiles.flat().filter(Boolean)
+}
+
 module.exports = {
   prototypeAppScripts: scripts,
   addNunjucksFilters,
@@ -268,5 +290,6 @@ module.exports = {
   encryptPassword,
   requestHttpsJson,
   sessionFileStoreQuietLogFn,
+  searchAndReplaceFiles,
   recursiveDirectoryContentsSync
 }
diff --git a/migrator/index.js b/migrator/index.js
index ddc3710823..04ffb58858 100644
--- a/migrator/index.js
+++ b/migrator/index.js
@@ -17,7 +17,8 @@ const {
   deleteEmptyDirectories,
   upgradeIfUnchanged,
   deleteIfUnchanged,
-  removeOldPatternIncludesFromSassFile
+  removeOldPatternIncludesFromSassFile,
+  updateUnbrandedLayouts
 } = require('./migration-steps')
 
 const supportPage = 'https://prototype-kit.service.gov.uk/docs/support'
@@ -143,6 +144,7 @@ async function migrate () {
       deleteUnusedDirectories(directoriesToDelete),
       upgradeIfUnchanged(filesToUpdateIfUnchanged),
       upgradeLayoutIfUnchanged(),
+      updateUnbrandedLayouts('app/views'),
       deleteIfUnchanged(filesToDeleteIfUnchanged),
       deleteIfUnchanged(patternsToDeleteIfUnchanged)
     ])
diff --git a/migrator/migration-steps.js b/migrator/migration-steps.js
index 48533a2b37..8d2f5fbba1 100644
--- a/migrator/migration-steps.js
+++ b/migrator/migration-steps.js
@@ -7,6 +7,7 @@ const fse = require('fs-extra')
 const lodash = require('lodash')
 
 // local dependencies
+const { searchAndReplaceFiles } = require('../lib/utils')
 const { appDir, projectDir, packageDir } = require('../lib/utils/paths')
 const config = require('../lib/config')
 const logger = require('./logger')
@@ -232,6 +233,15 @@ async function upgradeIfUnchanged (filePaths, starterFilePath, additionalStep) {
   }))
 }
 
+async function updateUnbrandedLayouts (dir) {
+  const results = await searchAndReplaceFiles(
+    path.join(projectDir, dir),
+    '"layout_unbranded.html"',
+    '"govuk-prototype-kit/layouts/unbranded.html"',
+    ['.html', '.njk'])
+  return results.flat()
+}
+
 module.exports = {
   getOldConfig,
   preflightChecks,
@@ -243,5 +253,6 @@ module.exports = {
   deleteUnusedDirectories,
   deleteEmptyDirectories,
   deleteIfUnchanged,
-  upgradeIfUnchanged
+  upgradeIfUnchanged,
+  updateUnbrandedLayouts
 }
diff --git a/migrator/migration-steps.spec.js b/migrator/migration-steps.spec.js
index 3f7bd9eae7..3cd4057931 100644
--- a/migrator/migration-steps.spec.js
+++ b/migrator/migration-steps.spec.js
@@ -21,6 +21,12 @@ jest.mock('./reporter', () => {
   }
 })
 
+jest.mock('../lib/utils', () => {
+  return {
+    searchAndReplaceFiles: jest.fn().mockResolvedValue([])
+  }
+})
+
 jest.mock('./file-helpers', () => {
   return {
     getFileAsLines: jest.fn().mockResolvedValue(true),
diff --git a/migrator/migrator.spec.js b/migrator/migrator.spec.js
index 216b85e631..0fd81192d6 100644
--- a/migrator/migrator.spec.js
+++ b/migrator/migrator.spec.js
@@ -21,6 +21,7 @@ jest.mock('./migration-steps', () => {
     deleteUnusedDirectories: jest.fn().mockResolvedValue(true),
     deleteEmptyDirectories: jest.fn().mockResolvedValue([true]),
     upgradeIfUnchanged: jest.fn(),
+    updateUnbrandedLayouts: jest.fn().mockResolvedValue(true),
     deleteIfUnchanged: jest.fn().mockResolvedValue([true, true, true]),
     removeOldPatternIncludesFromSassFile: jest.fn().mockResolvedValue(true)
   }