diff --git a/packages/block-library/src/post-date/edit.js b/packages/block-library/src/post-date/edit.js
index cfb5c57210600..01ac5edd4ba36 100644
--- a/packages/block-library/src/post-date/edit.js
+++ b/packages/block-library/src/post-date/edit.js
@@ -8,7 +8,11 @@ import clsx from 'clsx';
  */
 import { useEntityProp, store as coreStore } from '@wordpress/core-data';
 import { useMemo, useState } from '@wordpress/element';
-import { dateI18n, getSettings as getDateSettings } from '@wordpress/date';
+import {
+	dateI18n,
+	humanTimeDiff,
+	getSettings as getDateSettings,
+} from '@wordpress/date';
 import {
 	AlignmentControl,
 	BlockControls,
@@ -82,7 +86,9 @@ export default function PostDateEdit( {
 
 	let postDate = date ? (
 		<time dateTime={ dateI18n( 'c', date ) } ref={ setPopoverAnchor }>
-			{ dateI18n( format || siteFormat, date ) }
+			{ format === 'Time Ago'
+				? humanTimeDiff( date, new Date() )
+				: dateI18n( format || siteFormat, date ) }
 		</time>
 	) : (
 		dateLabel
diff --git a/packages/block-library/src/post-date/index.php b/packages/block-library/src/post-date/index.php
index bcfff02fc178d..1f06a91bb132d 100644
--- a/packages/block-library/src/post-date/index.php
+++ b/packages/block-library/src/post-date/index.php
@@ -20,8 +20,13 @@ function render_block_core_post_date( $attributes, $content, $block ) {
 		return '';
 	}
 
-	$post_ID          = $block->context['postId'];
-	$formatted_date   = get_the_date( empty( $attributes['format'] ) ? '' : $attributes['format'], $post_ID );
+	$post_ID = $block->context['postId'];
+
+	if ( 'Time Ago' === $attributes['format'] ) {
+		$formatted_date = human_time_diff( get_post_timestamp( $post_ID, 'date' ) ) . ' ' . __( 'ago' );
+	} else {
+		$formatted_date = get_the_date( empty( $attributes['format'] ) ? '' : $attributes['format'], $post_ID );
+	}
 	$unformatted_date = esc_attr( get_the_date( 'c', $post_ID ) );
 	$classes          = array();
 
@@ -38,7 +43,11 @@ function render_block_core_post_date( $attributes, $content, $block ) {
 	 */
 	if ( isset( $attributes['displayType'] ) && 'modified' === $attributes['displayType'] ) {
 		if ( get_the_modified_date( 'Ymdhi', $post_ID ) > get_the_date( 'Ymdhi', $post_ID ) ) {
-			$formatted_date   = get_the_modified_date( empty( $attributes['format'] ) ? '' : $attributes['format'], $post_ID );
+			if ( 'Time Ago' === $attributes['format'] ) {
+				$formatted_date = human_time_diff( get_post_timestamp( $post_ID, 'modified' ) ) . ' ' . __( 'ago' );
+			} else {
+				$formatted_date = get_the_modified_date( empty( $attributes['format'] ) ? '' : $attributes['format'], $post_ID );
+			}
 			$unformatted_date = esc_attr( get_the_modified_date( 'c', $post_ID ) );
 			$classes[]        = 'wp-block-post-date__modified-date';
 		} else {