diff --git a/CHANGELOG.md b/CHANGELOG.md
index 266dbe7b..e4f55395 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,8 @@ Note: In this file, do not use the hard wrap in the middle of a sentence for com
 
 ## [Unreleased]
 
+- Update `biome@latest` to 2.5.9.
+
 ## [2.86.3] - 2026-08-18
 
 - Update `prek@latest` to 0.4.14.
diff --git a/manifests/biome.json b/manifests/biome.json
index c1f3a6cf..0f2eec84 100644
--- a/manifests/biome.json
+++ b/manifests/biome.json
@@ -2,13 +2,13 @@
   "rust_crate": null,
   "template": null,
   "latest": {
-    "version": "2.5.8"
+    "version": "2.5.9"
   },
   "2": {
-    "version": "2.5.8"
+    "version": "2.5.9"
   },
   "2.5": {
-    "version": "2.5.8"
+    "version": "2.5.9"
   },
   "2.5.9": {
     "x86_64_linux_musl": {