diff --git a/src/wp-includes/html-api/class-wp-html-template.php b/src/wp-includes/html-api/class-wp-html-template.php
index 3169b10dfc317..14ee1b3c670e9 100644
--- a/src/wp-includes/html-api/class-wp-html-template.php
+++ b/src/wp-includes/html-api/class-wp-html-template.php
@@ -26,7 +26,7 @@ class WP_HTML_Template extends WP_HTML_Tag_Processor {
 	 *
 	 * This function looks for placeholders in the template string and will replace
 	 * them with appropriately-escaped substitutions from the given arguments, if
-	 * provided and if those arguments are strings.
+	 * provided and if those arguments are strings or valid attribute values.
 	 *
 	 * Example:
 	 *
@@ -64,7 +64,7 @@ class WP_HTML_Template extends WP_HTML_Tag_Processor {
 	 *    If provided any other type of value the attribute will be ignored and its existing value persists.
 	 *
 	 *  - If multiple HTML attributes are specified for a given tag they will be applied as if calling
-	 *    `set_attribute()` in the order they are specified in the temlpate. This includes any attributes
+	 *    `set_attribute()` in the order they are specified in the template. This includes any attributes
 	 *    assigned through the attribute spread syntax.
 	 *
 	 *  - Substitutions in text nodes may only contain string values. If provided any other type of value
@@ -74,7 +74,7 @@ class WP_HTML_Template extends WP_HTML_Tag_Processor {
 	 *    it may provide the ability to nest pre-rendered HTML into the template, but this functionality
 	 *    is deferred for a future update.
 	 *
-	 *  - This function will not replace content inside of TEXTAREA, TITLE, SCRIPT, or STYLE elements.
+	 *  - This function will not replace content inside of SCRIPT, or STYLE elements.
 	 *
 	 * @since 6.5.0
 	 *
@@ -162,6 +162,25 @@ static function ( $matches ) use ( $args ) {
 						$processor->set_attribute( $attribute_name, $new_value );
 					}
 				}
+
+				// Update TEXTAREA and TITLE contents.
+				$tag_name = $processor->get_tag();
+				if ( 'TEXTAREA' === $tag_name || 'TITLE' === $tag_name ) {
+					// Replace placeholders inside these RCDATA tags.
+					$new_text = preg_replace_callback(
+						'~</%([^>]+)>~',
+						static function ( $matches ) use ( $args ) {
+							return is_string( $args[ $matches[1] ] )
+								? $args[ $matches[1] ]
+								: '';
+						},
+						$text
+					);
+
+					if ( $new_text !== $text ) {
+						$processor->set_modifiable_text( $new_text );
+					}
+				}
 			}
 		}
 
diff --git a/src/wp-includes/html-api/class-wp-html.php b/src/wp-includes/html-api/class-wp-html.php
index 6443acac91508..a1c38e866af59 100644
--- a/src/wp-includes/html-api/class-wp-html.php
+++ b/src/wp-includes/html-api/class-wp-html.php
@@ -20,7 +20,7 @@ class WP_HTML {
 	 *
 	 * This function looks for placeholders in the template string and will replace
 	 * them with appropriately-escaped substitutions from the given arguments, if
-	 * provided and if those arguments are strings.
+	 * provided and if those arguments are strings or valid attribute values.
 	 *
 	 * Example:
 	 *
@@ -58,7 +58,7 @@ class WP_HTML {
 	 *    If provided any other type of value the attribute will be ignored and its existing value persists.
 	 *
 	 *  - If multiple HTML attributes are specified for a given tag they will be applied as if calling
-	 *    `set_attribute()` in the order they are specified in the temlpate. This includes any attributes
+	 *    `set_attribute()` in the order they are specified in the template. This includes any attributes
 	 *    assigned through the attribute spread syntax.
 	 *
 	 *  - Substitutions in text nodes may only contain string values. If provided any other type of value
@@ -68,6 +68,8 @@ class WP_HTML {
 	 *    it may provide the ability to nest pre-rendered HTML into the template, but this functionality
 	 *    is deferred for a future update.
 	 *
+	 *  - This function will not replace content inside of SCRIPT, or STYLE elements.
+	 *
 	 * @since 6.5.0
 	 *
 	 * @access private
diff --git a/tests/phpunit/tests/html-api/wpHtmlTemplate.php b/tests/phpunit/tests/html-api/wpHtmlTemplate.php
index cc63eba954fd2..dd4859fb2f14b 100644
--- a/tests/phpunit/tests/html-api/wpHtmlTemplate.php
+++ b/tests/phpunit/tests/html-api/wpHtmlTemplate.php
@@ -85,4 +85,22 @@ public function test_cannot_break_out_of_tag_with_malicious_attribute_name() {
 			"Should not have found any other tags but found {$processor->get_tag()} instead."
 		);
 	}
+
+	/**
+	 * Ensures that basic replacement inside a TEXTAREA subtitutes placeholders.
+	 *
+	 * @ticket 60229
+	 */
+	public function test_replaces_textarea_placeholders() {
+		$html = WP_HTML_Template::render(
+			'<textarea>The </%big> one.</textarea>',
+			array( 'big' => '<HUGE> (</textarea>)' )
+		);
+
+		$this->assertSame(
+			'<textarea>The <HUGE> (&lt;/textarea>) one.</textarea>',
+			$html,
+			'Should have replaced placeholder with RCDATA escaping rules.'
+		);
+	}
 }