diff --git a/packages/docusaurus-theme-classic/src/theme/LayoutHead/index.tsx b/packages/docusaurus-theme-classic/src/theme/LayoutHead/index.tsx
index c0cfc29cf6..c263477449 100644
--- a/packages/docusaurus-theme-classic/src/theme/LayoutHead/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/LayoutHead/index.tsx
@@ -81,7 +81,10 @@ export default function LayoutHead(props: Props): JSX.Element {
           <meta property="og:description" content={description} />
         )}
         {keywords && keywords.length && (
-          <meta name="keywords" content={keywords.join(',')} />
+          <meta
+            name="keywords"
+            content={Array.isArray(keywords) ? keywords.join(',') : keywords}
+          />
         )}
         {metaImage && <meta property="og:image" content={metaImageUrl} />}
         {metaImage && <meta name="twitter:image" content={metaImageUrl} />}
diff --git a/packages/docusaurus-theme-classic/src/types.d.ts b/packages/docusaurus-theme-classic/src/types.d.ts
index d3e889ade8..5355db8b88 100644
--- a/packages/docusaurus-theme-classic/src/types.d.ts
+++ b/packages/docusaurus-theme-classic/src/types.d.ts
@@ -237,7 +237,7 @@ declare module '@theme/Layout' {
     noFooter?: boolean;
     description?: string;
     image?: string;
-    keywords?: string[];
+    keywords?: string | string[];
     permalink?: string;
     wrapperClassName?: string;
     searchMetadatas?: {