diff --git a/.changeset/forty-goats-warn.md b/.changeset/forty-goats-warn.md
new file mode 100644
index 000000000..6f0d863e6
--- /dev/null
+++ b/.changeset/forty-goats-warn.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes client:only CSS
diff --git a/packages/astro/src/core/build/internal.ts b/packages/astro/src/core/build/internal.ts
index d74722b1a..d9a21a7de 100644
--- a/packages/astro/src/core/build/internal.ts
+++ b/packages/astro/src/core/build/internal.ts
@@ -1,7 +1,8 @@
-import type { RouteData } from '../../@types/astro';
+import type { AstroConfig, RouteData } from '../../@types/astro';
 import type { RenderedChunk } from 'rollup';
 import type { PageBuildData, ViteID } from './types';
 
+import { fileURLToPath } from 'url';
 import { viteID } from '../util.js';
 
 export interface BuildInternals {
@@ -25,6 +26,11 @@ export interface BuildInternals {
 	 */
 	pagesByViteID: Map<ViteID, PageBuildData>;
 
+	/**
+	 * A map for page-specific information by a client:only component
+	 */
+	pagesByClientOnly: Map<string, Set<PageBuildData>>;
+
 	/**
 	 * chunkToReferenceIdMap maps them to a hash id used to find the final file.
 	 * @deprecated This Map is only used for the legacy build.
@@ -73,6 +79,7 @@ export function createBuildInternals(): BuildInternals {
 
 		pagesByComponent: new Map(),
 		pagesByViteID: new Map(),
+		pagesByClientOnly: new Map(),
 	};
 }
 
@@ -88,6 +95,30 @@ export function trackPageData(
 	internals.pagesByViteID.set(viteID(componentURL), pageData);
 }
 
+/**
+ * Tracks client-only components to the pages they are associated with.
+ */
+export function trackClientOnlyPageDatas(
+	internals: BuildInternals,
+	pageData: PageBuildData,
+	clientOnlys: string[],
+	astroConfig: AstroConfig,
+) {
+	for(const clientOnlyComponent of clientOnlys) {
+		const coPath = viteID(new URL('.' + clientOnlyComponent, astroConfig.root));
+		let pageDataSet: Set<PageBuildData>;
+		if(internals.pagesByClientOnly.has(coPath)) {
+			pageDataSet = internals.pagesByClientOnly.get(coPath)!;
+		} else {
+			pageDataSet = new Set<PageBuildData>();
+			internals.pagesByClientOnly.set(coPath, pageDataSet);
+		}
+		pageDataSet.add(pageData);
+	}
+}
+
+
+
 export function* getPageDatasByChunk(
 	internals: BuildInternals,
 	chunk: RenderedChunk
@@ -100,6 +131,22 @@ export function* getPageDatasByChunk(
 	}
 }
 
+export function* getPageDatasByClientOnlyChunk(
+	internals: BuildInternals,
+	chunk: RenderedChunk
+): Generator<PageBuildData, void, unknown> {
+	const pagesByClientOnly = internals.pagesByClientOnly;
+	if(pagesByClientOnly.size) {
+		for (const [modulePath] of Object.entries(chunk.modules)) {
+			if (pagesByClientOnly.has(modulePath)) {
+				for(const pageData of pagesByClientOnly.get(modulePath)!) {
+					yield pageData;
+				}
+			}
+		}
+	}
+}
+
 export function getPageDataByComponent(
 	internals: BuildInternals,
 	component: string
diff --git a/packages/astro/src/core/build/static-build.ts b/packages/astro/src/core/build/static-build.ts
index 40107844d..6be7ee4e2 100644
--- a/packages/astro/src/core/build/static-build.ts
+++ b/packages/astro/src/core/build/static-build.ts
@@ -1,5 +1,5 @@
 import type { RollupOutput } from 'rollup';
-import type { BuildInternals } from '../../core/build/internal.js';
+import { BuildInternals, trackClientOnlyPageDatas } from '../../core/build/internal.js';
 import type { ViteConfigWithSSR } from '../create-vite';
 import type { PageBuildData, StaticBuildOptions } from './types';
 import glob from 'fast-glob';
@@ -54,13 +54,17 @@ export async function staticBuild(opts: StaticBuildOptions) {
 			const [renderers, mod] = pageData.preload;
 			const metadata = mod.$$metadata;
 
+			// Track client:only usage so we can map their CSS back to the Page they are used in.
+			const clientOnlys = Array.from(metadata.clientOnlyComponentPaths());
+			trackClientOnlyPageDatas(internals, pageData, clientOnlys, astroConfig);
+
 			const topLevelImports = new Set([
 				// Any component that gets hydrated
 				// 'components/Counter.jsx'
 				// { 'components/Counter.jsx': 'counter.hash.js' }
 				...metadata.hydratedComponentPaths(),
 				// Client-only components
-				...metadata.clientOnlyComponentPaths(),
+				...clientOnlys,
 				// Any hydration directive like astro/client/idle.js
 				...metadata.hydrationDirectiveSpecifiers(),
 				// The client path for each renderer
@@ -148,6 +152,7 @@ async function ssrBuild(opts: StaticBuildOptions, internals: BuildInternals, inp
 			rollupPluginAstroBuildCSS({
 				internals,
 				legacy: false,
+				target: 'server'
 			}),
 			...(viteConfig.plugins || []),
 			// SSR needs to be last
@@ -218,6 +223,7 @@ async function clientBuild(
 			rollupPluginAstroBuildCSS({
 				internals,
 				legacy: false,
+				target: 'client'
 			}),
 			...(viteConfig.plugins || []),
 		],
diff --git a/packages/astro/src/vite-plugin-build-css/index.ts b/packages/astro/src/vite-plugin-build-css/index.ts
index 150cd7451..de62a9933 100644
--- a/packages/astro/src/vite-plugin-build-css/index.ts
+++ b/packages/astro/src/vite-plugin-build-css/index.ts
@@ -9,6 +9,7 @@ import {
 	getPageDatasByChunk,
 	getPageDataByViteID,
 	hasPageDataByViteID,
+	getPageDatasByClientOnlyChunk,
 } from '../core/build/internal.js';
 
 const PLUGIN_NAME = '@astrojs/rollup-plugin-build-css';
@@ -54,6 +55,7 @@ function isRawOrUrlModule(id: string) {
 interface PluginOptions {
 	internals: BuildInternals;
 	legacy: boolean;
+	target: 'client' | 'server';
 }
 
 export function rollupPluginAstroBuildCSS(options: PluginOptions): VitePlugin {
@@ -172,7 +174,7 @@ export function rollupPluginAstroBuildCSS(options: PluginOptions): VitePlugin {
 		},
 
 		async renderChunk(_code, chunk) {
-			if (!legacy) return null;
+			if (options.target === 'server') return null;
 
 			let chunkCSS = '';
 			let isPureCSS = true;
@@ -207,6 +209,10 @@ export function rollupPluginAstroBuildCSS(options: PluginOptions): VitePlugin {
 				for (const pageData of getPageDatasByChunk(internals, chunk)) {
 					pageData.css.add(fileName);
 				}
+				// Adds this CSS for client:only components to the appropriate page
+				for (const pageData of getPageDatasByClientOnlyChunk(internals, chunk)) {
+					pageData.css.add(fileName);
+				}
 			}
 
 			return null;
diff --git a/packages/astro/test/astro-client-only.test.js b/packages/astro/test/astro-client-only.test.js
index 812b7229b..dcd7faf17 100644
--- a/packages/astro/test/astro-client-only.test.js
+++ b/packages/astro/test/astro-client-only.test.js
@@ -1,5 +1,5 @@
 import { expect } from 'chai';
-import cheerio from 'cheerio';
+import { load as cheerioLoad } from 'cheerio';
 import { loadFixture } from './test-utils.js';
 
 describe('Client only components', () => {
@@ -14,7 +14,7 @@ describe('Client only components', () => {
 
 	it('Loads pages using client:only hydrator', async () => {
 		const html = await fixture.readFile('/index.html');
-		const $ = cheerio.load(html);
+		const $ = cheerioLoad(html);
 
 		// test 1: <astro-root> is empty
 		expect($('astro-root').html()).to.equal('');
@@ -24,4 +24,10 @@ describe('Client only components', () => {
 		// test 2: svelte renderer is on the page
 		expect(/import\(".\/entry.*/g.test(script)).to.be.ok;
 	});
+
+	it('Adds the CSS to the page', async () => {
+		const html = await fixture.readFile('/index.html');
+		const $ = cheerioLoad(html);
+		expect($('link[rel=stylesheet]')).to.have.lengthOf(2);
+	})
 });
diff --git a/packages/astro/test/fixtures/astro-client-only/astro.config.mjs b/packages/astro/test/fixtures/astro-client-only/astro.config.mjs
index 77fdcd1b9..1c8866ea7 100644
--- a/packages/astro/test/fixtures/astro-client-only/astro.config.mjs
+++ b/packages/astro/test/fixtures/astro-client-only/astro.config.mjs
@@ -1,7 +1,8 @@
 import { defineConfig } from 'astro/config';
 import svelte from '@astrojs/svelte';
+import react from '@astrojs/react';
 
 // https://astro.build/config
 export default defineConfig({
-	integrations: [svelte()],
+	integrations: [svelte(), react()],
 });
diff --git a/packages/astro/test/fixtures/astro-client-only/package.json b/packages/astro/test/fixtures/astro-client-only/package.json
index 038e6f99d..96f83eac2 100644
--- a/packages/astro/test/fixtures/astro-client-only/package.json
+++ b/packages/astro/test/fixtures/astro-client-only/package.json
@@ -4,6 +4,7 @@
   "private": true,
   "dependencies": {
     "@astrojs/svelte": "workspace:*",
+    "@astrojs/react": "workspace:*",
     "astro": "workspace:*"
   }
 }
diff --git a/packages/astro/test/fixtures/astro-client-only/src/components/JSXComponent.jsx b/packages/astro/test/fixtures/astro-client-only/src/components/JSXComponent.jsx
new file mode 100644
index 000000000..e9d2411d1
--- /dev/null
+++ b/packages/astro/test/fixtures/astro-client-only/src/components/JSXComponent.jsx
@@ -0,0 +1,6 @@
+import React from 'react';
+import './global.css';
+
+export default function() {
+	return <div>i am react</div>
+}
diff --git a/packages/astro/test/fixtures/astro-client-only/src/components/PersistentCounter.svelte b/packages/astro/test/fixtures/astro-client-only/src/components/PersistentCounter.svelte
index 92d005415..855be29ea 100644
--- a/packages/astro/test/fixtures/astro-client-only/src/components/PersistentCounter.svelte
+++ b/packages/astro/test/fixtures/astro-client-only/src/components/PersistentCounter.svelte
@@ -12,7 +12,11 @@
     count -= 1;
   }
 </script>
-
+<style>
+	button {
+		background: yellowgreen;
+	}
+</style>
 <div class="counter">
   <button on:click={subtract}>-</button>
   <pre>{ count }</pre>
diff --git a/packages/astro/test/fixtures/astro-client-only/src/components/global.css b/packages/astro/test/fixtures/astro-client-only/src/components/global.css
new file mode 100644
index 000000000..e495b6de9
--- /dev/null
+++ b/packages/astro/test/fixtures/astro-client-only/src/components/global.css
@@ -0,0 +1,3 @@
+body {
+	font-family: 'Courier New', Courier, monospace;
+}
diff --git a/packages/astro/test/fixtures/astro-client-only/src/pages/index.astro b/packages/astro/test/fixtures/astro-client-only/src/pages/index.astro
index cb277d194..bf239197f 100644
--- a/packages/astro/test/fixtures/astro-client-only/src/pages/index.astro
+++ b/packages/astro/test/fixtures/astro-client-only/src/pages/index.astro
@@ -1,9 +1,11 @@
 ---
 import PersistentCounter from '../components/PersistentCounter.svelte';
+import ReactComponent from '../components/JSXComponent.jsx';
 ---
 <html>
 <head><title>Client only pages</title></head>
 <body>
   <PersistentCounter client:only />
+	<ReactComponent client:only="react" />
 </body>
 </html>
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 445165259..2c8331563 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -684,9 +684,11 @@ importers:
 
   packages/astro/test/fixtures/astro-client-only:
     specifiers:
+      '@astrojs/react': workspace:*
       '@astrojs/svelte': workspace:*
       astro: workspace:*
     dependencies:
+      '@astrojs/react': link:../../../../integrations/react
       '@astrojs/svelte': link:../../../../integrations/svelte
       astro: link:../../..