diff --git a/CHANGELOG-WIP.md b/CHANGELOG-WIP.md
deleted file mode 100644
index 8187aa7071c..00000000000
--- a/CHANGELOG-WIP.md
+++ /dev/null
@@ -1,17 +0,0 @@
-# Release Notes for Craft CMS 3.9 (WIP)
-
-### Content Management
-
-### Accessibility
-
-### Administration
-
-### Development
-
-### Extensibility
-- `craft\services\Assets::getAllDescendantFolders()` now has an `$asTree` argument. ([#13535](https://github.com/craftcms/cms/discussions/13535))
-
-### System
-- Updated Yii to 2.0.48.1. ([#13444](https://github.com/craftcms/cms/pull/13444))
-- Loosened the Composer constraint to `^2.2.19`. ([#13396](https://github.com/craftcms/cms/discussions/13396))
-- Internal Composer operations now use a bundled `composer.phar` file, rather than Composer’s PHP API. ([#13519](https://github.com/craftcms/cms/pull/13519))   
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6f9d109863c..30b42bf7553 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,11 @@
 # Release Notes for Craft CMS 3.x
 
-## Unreleased
+## 3.9.0 - 2023-08-22
 
+- Updated Yii to 2.0.48.1. ([#13444](https://github.com/craftcms/cms/pull/13444))
+- Loosened the Composer constraint to `^2.2.19`. ([#13396](https://github.com/craftcms/cms/discussions/13396))
+- Internal Composer operations now use a bundled `composer.phar` file, rather than Composer’s PHP API. ([#13519](https://github.com/craftcms/cms/pull/13519))
+- `craft\services\Assets::getAllDescendantFolders()` now has an `$asTree` argument. ([#13535](https://github.com/craftcms/cms/discussions/13535))
 - Fixed a bug where asset exports could be blank if only subfolders were selected.
 
 ## 3.8.17 - 2023-08-08
diff --git a/src/config/app.php b/src/config/app.php
index 733dedf339e..505c6eed2a6 100644
--- a/src/config/app.php
+++ b/src/config/app.php
@@ -3,7 +3,7 @@
 return [
     'id' => 'CraftCMS',
     'name' => 'Craft CMS',
-    'version' => '3.8.17',
+    'version' => '3.9.0',
     'schemaVersion' => '3.8.0.1',
     'minVersionRequired' => '2.6.2788',
     'basePath' => dirname(__DIR__), // Defines the @app alias