diff --git a/.changeset/purple-mirrors-smile.md b/.changeset/purple-mirrors-smile.md
new file mode 100644
index 000000000..879c45058
--- /dev/null
+++ b/.changeset/purple-mirrors-smile.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix edge case where Astro component would render [Object object] when using MDX
diff --git a/packages/astro/src/runtime/server/index.ts b/packages/astro/src/runtime/server/index.ts
index 9a655d380..150937a9d 100644
--- a/packages/astro/src/runtime/server/index.ts
+++ b/packages/astro/src/runtime/server/index.ts
@@ -752,7 +752,7 @@ export async function renderToString(
 
 	let html = '';
 	for await (const chunk of renderAstroComponent(Component)) {
-		html += chunk;
+		html += stringifyChunk(result, chunk);
 	}
 	return html;
 }