diff --git a/packages/block-library/src/avatar/index.php b/packages/block-library/src/avatar/index.php
index d404fb81ca357..303b35458eb1a 100644
--- a/packages/block-library/src/avatar/index.php
+++ b/packages/block-library/src/avatar/index.php
@@ -31,7 +31,18 @@ function render_block_core_avatar( $attributes, $content, $block ) {
 		: '';
 
 	if ( ! isset( $block->context['commentId'] ) ) {
-		$author_id   = isset( $attributes['userId'] ) ? $attributes['userId'] : get_post_field( 'post_author', $block->context['postId'] );
+		if ( isset( $attributes['userId'] ) ) {
+			$author_id = $attributes['userId'];
+		} elseif ( isset( $block->context['postId'] ) ) {
+			$author_id = get_post_field( 'post_author', $block->context['postId'] );
+		} else {
+			$author_id = get_query_var( 'author' );
+		}
+
+		if ( empty( $author_id ) ) {
+			return '';
+		}
+
 		$author_name = get_the_author_meta( 'display_name', $author_id );
 		// translators: %s is the Author name.
 		$alt          = sprintf( __( '%s Avatar' ), $author_name );
diff --git a/packages/block-library/src/post-author-biography/index.php b/packages/block-library/src/post-author-biography/index.php
index 3ea6ecbd9b46a..7381e7a5d229b 100644
--- a/packages/block-library/src/post-author-biography/index.php
+++ b/packages/block-library/src/post-author-biography/index.php
@@ -15,10 +15,11 @@
  */
 function render_block_core_post_author_biography( $attributes, $content, $block ) {
 	if ( ! isset( $block->context['postId'] ) ) {
-		return '';
+		$author_id = get_query_var( 'author' );
+	} else {
+		$author_id = get_post_field( 'post_author', $block->context['postId'] );
 	}
 
-	$author_id = get_post_field( 'post_author', $block->context['postId'] );
 	if ( empty( $author_id ) ) {
 		return '';
 	}
diff --git a/packages/block-library/src/post-author-name/index.php b/packages/block-library/src/post-author-name/index.php
index c5c6d142e06dd..8f2c035b093b6 100644
--- a/packages/block-library/src/post-author-name/index.php
+++ b/packages/block-library/src/post-author-name/index.php
@@ -15,10 +15,11 @@
  */
 function render_block_core_post_author_name( $attributes, $content, $block ) {
 	if ( ! isset( $block->context['postId'] ) ) {
-		return '';
+		$author_id = get_query_var( 'author' );
+	} else {
+		$author_id = get_post_field( 'post_author', $block->context['postId'] );
 	}
 
-	$author_id = get_post_field( 'post_author', $block->context['postId'] );
 	if ( empty( $author_id ) ) {
 		return '';
 	}