diff --git a/.changeset/fix-bundle-ui-step.md b/.changeset/fix-bundle-ui-step.md
new file mode 100644
index 0000000000..19434812a9
--- /dev/null
+++ b/.changeset/fix-bundle-ui-step.md
@@ -0,0 +1,5 @@
+---
+'@shopify/app': patch
+---
+
+Fix `shopify app build` for some UI extensions
diff --git a/packages/app/src/cli/services/build/steps/bundle-ui-step.test.ts b/packages/app/src/cli/services/build/steps/bundle-ui-step.test.ts
index c87aadb12a..1a7a7a0cdd 100644
--- a/packages/app/src/cli/services/build/steps/bundle-ui-step.test.ts
+++ b/packages/app/src/cli/services/build/steps/bundle-ui-step.test.ts
@@ -1,4 +1,5 @@
 import {executeBundleUIStep} from './bundle-ui-step.js'
+import * as generateManifest from './include-assets/generate-manifest.js'
 import * as buildExtension from '../extension.js'
 import {BundleUIStep, BuildContext} from '../client-steps.js'
 import {ExtensionInstance} from '../../../models/extensions/extension-instance.js'
@@ -7,6 +8,7 @@ import * as fs from '@shopify/cli-kit/node/fs'
 
 vi.mock('@shopify/cli-kit/node/fs')
 vi.mock('../extension.js')
+vi.mock('./include-assets/generate-manifest.js')
 
 describe('executeBundleUIStep', () => {
   let mockContext: BuildContext
@@ -46,4 +48,34 @@ describe('executeBundleUIStep', () => {
     // Then
     expect(fs.copyFile).toHaveBeenCalledWith('/test/extension/dist', '/bundle/handle')
   })
+
+  test('skips the copy when local and bundle output directories resolve to the same path but differ as strings', async () => {
+    mockContext.extension.outputPath = '/test/./extension/dist/handle.js'
+    vi.mocked(buildExtension.buildUIExtension).mockResolvedValue('/test/extension/dist/handle.js')
+
+    await executeBundleUIStep(step, mockContext)
+
+    expect(fs.copyFile).not.toHaveBeenCalled()
+  })
+
+  test('skips manifest generation when local and bundle output directories resolve to the same path', async () => {
+    const stepWithManifest: BundleUIStep = {
+      id: 'bundle-ui',
+      name: 'Bundle UI Extension',
+      type: 'bundle_ui',
+      config: {generatesAssetsManifest: true},
+    }
+    mockContext.extension.outputPath = '/test/./extension/dist/handle.js'
+    mockContext.extension.configuration = {
+      extension_points: [
+        {target: 'admin.product-details.action.render', build_manifest: {assets: {main: {filepath: 'main.js'}}}},
+      ],
+    } as ExtensionInstance['configuration']
+    vi.mocked(buildExtension.buildUIExtension).mockResolvedValue('/test/extension/dist/handle.js')
+
+    await executeBundleUIStep(stepWithManifest, mockContext)
+
+    expect(fs.copyFile).not.toHaveBeenCalled()
+    expect(generateManifest.createOrUpdateManifestFile).not.toHaveBeenCalled()
+  })
 })
diff --git a/packages/app/src/cli/services/build/steps/bundle-ui-step.ts b/packages/app/src/cli/services/build/steps/bundle-ui-step.ts
index ace25649bb..580550b053 100644
--- a/packages/app/src/cli/services/build/steps/bundle-ui-step.ts
+++ b/packages/app/src/cli/services/build/steps/bundle-ui-step.ts
@@ -2,7 +2,7 @@ import {createOrUpdateManifestFile} from './include-assets/generate-manifest.js'
 import {buildUIExtension} from '../extension.js'
 import {BuildManifest} from '../../../models/extensions/specifications/ui_extension.js'
 import {copyFile} from '@shopify/cli-kit/node/fs'
-import {dirname, joinPath} from '@shopify/cli-kit/node/path'
+import {dirname, joinPath, resolvePath} from '@shopify/cli-kit/node/path'
 import type {BundleUIStep, BuildContext} from '../client-steps.js'
 
 interface ExtensionPointWithBuildManifest {
@@ -26,9 +26,11 @@ export async function executeBundleUIStep(step: BundleUIStep, context: BuildCont
   const bundleOutputDir = step.config?.bundleFolder
     ? joinPath(dirname(context.extension.outputPath), step.config.bundleFolder)
     : dirname(context.extension.outputPath)
-  if (localOutputDir !== bundleOutputDir) {
-    await copyFile(localOutputDir, bundleOutputDir)
-  }
+
+  // If the final output path is the same as the local one: don't copy the results and don't generate manifests.
+  if (resolvePath(localOutputDir) === resolvePath(bundleOutputDir)) return
+
+  await copyFile(localOutputDir, bundleOutputDir)
 
   if (!step.config?.generatesAssetsManifest) return