diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 02f17d9d..76d5538a 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.8.1"
+  ".": "0.9.0"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ce749387..409f2a2a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,18 @@
 # Changelog
 
+## [0.9.0](https://github.com/eslint/css/compare/css-v0.8.1...css-v0.9.0) (2025-06-12)
+
+
+### Features
+
+* add `relative-font-units` rule ([#133](https://github.com/eslint/css/issues/133)) ([ce256da](https://github.com/eslint/css/commit/ce256da671503792e74ad2113daa72319361c8b5))
+* Validate property values containing variables ([#148](https://github.com/eslint/css/issues/148)) ([9fb07fa](https://github.com/eslint/css/commit/9fb07fab74849e31ec363c75ce0d405a6a3108ec))
+
+
+### Bug Fixes
+
+* Upgrade @eslint/css-tree to update syntax support ([#173](https://github.com/eslint/css/issues/173)) ([8909277](https://github.com/eslint/css/commit/8909277ec65d3e75336070274d13fb390c710069)), closes [#159](https://github.com/eslint/css/issues/159)
+
 ## [0.8.1](https://github.com/eslint/css/compare/css-v0.8.0...css-v0.8.1) (2025-05-16)
 
 
diff --git a/jsr.json b/jsr.json
index 9ee24767..b40312ec 100644
--- a/jsr.json
+++ b/jsr.json
@@ -1,6 +1,6 @@
 {
   "name": "@eslint/css",
-  "version": "0.8.1",
+  "version": "0.9.0",
   "exports": {
     ".": "./dist/esm/index.js",
     "./syntax": "./dist/esm/syntax/index.js"
diff --git a/package.json b/package.json
index 6242855a..26a74f7c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@eslint/css",
-  "version": "0.8.1",
+  "version": "0.9.0",
   "description": "CSS linting plugin for ESLint",
   "author": "Nicholas C. Zakas",
   "type": "module",
diff --git a/src/index.js b/src/index.js
index f6a30b18..92af717f 100644
--- a/src/index.js
+++ b/src/index.js
@@ -26,7 +26,7 @@ import useBaseline from "./rules/use-baseline.js";
 const plugin = {
 	meta: {
 		name: "@eslint/css",
-		version: "0.8.1", // x-release-please-version
+		version: "0.9.0", // x-release-please-version
 	},
 	languages: {
 		css: new CSSLanguage(),