diff --git a/.changeset/sharp-onions-search.md b/.changeset/sharp-onions-search.md
new file mode 100644
index 0000000000..a6d290af39
--- /dev/null
+++ b/.changeset/sharp-onions-search.md
@@ -0,0 +1,5 @@
+---
+"@astrojs/starlight": patch
+---
+
+Updates file tree icon mapping to correctly map `.cjs` and `.mjs` extensions in several contexts
diff --git a/packages/starlight/user-components/file-tree-icons.ts b/packages/starlight/user-components/file-tree-icons.ts
index d8c6af3808..2e9b58101f 100644
--- a/packages/starlight/user-components/file-tree-icons.ts
+++ b/packages/starlight/user-components/file-tree-icons.ts
@@ -44,6 +44,8 @@ export const definitions: Definitions = {
 		COMMIT_EDITMSG: 'seti:git',
 		MERGE_MSG: 'seti:git',
 		'karma.conf.js': 'seti:karma',
+		'karma.conf.cjs': 'seti:karma',
+		'karma.conf.mjs': 'seti:karma',
 		'karma.conf.coffee': 'seti:karma',
 		'README.md': 'seti:info',
 		'README.txt': 'seti:info',
@@ -74,6 +76,7 @@ export const definitions: Definitions = {
 		'WORKSPACE.bazel': 'seti:bazel',
 		'bower.json': 'seti:bower',
 		'Bower.json': 'seti:bower',
+		'eslint.config.js': 'seti:eslint',
 		'firebase.json': 'seti:firebase',
 		geckodriver: 'seti:firefox',
 		'Gruntfile.js': 'seti:grunt',
@@ -91,22 +94,28 @@ export const definitions: Definitions = {
 		'sass-lint.yml': 'seti:sass',
 		'stylelint.config.js': 'seti:stylelint',
 		'stylelint.config.cjs': 'seti:stylelint',
+		'stylelint.config.mjs': 'seti:stylelint',
 		'yarn.clean': 'seti:yarn',
 		'yarn.lock': 'seti:yarn',
 		'webpack.config.js': 'seti:webpack',
 		'webpack.config.cjs': 'seti:webpack',
+		'webpack.config.mjs': 'seti:webpack',
 		'webpack.config.ts': 'seti:webpack',
 		'webpack.config.build.js': 'seti:webpack',
 		'webpack.config.build.cjs': 'seti:webpack',
+		'webpack.config.build.mjs': 'seti:webpack',
 		'webpack.config.build.ts': 'seti:webpack',
 		'webpack.common.js': 'seti:webpack',
 		'webpack.common.cjs': 'seti:webpack',
+		'webpack.common.mjs': 'seti:webpack',
 		'webpack.common.ts': 'seti:webpack',
 		'webpack.dev.js': 'seti:webpack',
 		'webpack.dev.cjs': 'seti:webpack',
+		'webpack.dev.mjs': 'seti:webpack',
 		'webpack.dev.ts': 'seti:webpack',
 		'webpack.prod.js': 'seti:webpack',
 		'webpack.prod.cjs': 'seti:webpack',
+		'webpack.prod.mjs': 'seti:webpack',
 		'webpack.prod.ts': 'seti:webpack',
 		'npm-debug.log': 'seti:npm_ignored',
 	},
@@ -218,8 +227,16 @@ export const definitions: Definitions = {
 		'.properties': 'seti:java',
 		'.js': 'seti:javascript',
 		'.js.map': 'seti:javascript',
+		'.cjs': 'seti:javascript',
+		'.cjs.map': 'seti:javascript',
+		'.mjs': 'seti:javascript',
+		'.mjs.map': 'seti:javascript',
 		'.spec.js': 'seti:javascript',
+		'.spec.cjs': 'seti:javascript',
+		'.spec.mjs': 'seti:javascript',
 		'.test.js': 'seti:javascript',
+		'.test.cjs': 'seti:javascript',
+		'.test.mjs': 'seti:javascript',
 		'.es': 'seti:javascript',
 		'.es5': 'seti:javascript',
 		'.es6': 'seti:javascript',