diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/wpLinkAjax.php b/tests/phpunit/tests/admin/includes/ajax-actions/wpLinkAjax.php
new file mode 100644
index 0000000000000..a081618ad0f6d
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/wpLinkAjax.php
@@ -0,0 +1,160 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_wp_link_ajax() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 3.1.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_wp_link_ajax
+ */
+class Tests_wp_ajax_wp_link_ajax extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Tests successful search using the 'search' parameter.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_wp_link_ajax_search_success(): void {
+		$post = self::factory()->post->create_and_get(
+			array(
+				'post_title'  => 'Test Link Search',
+				'post_status' => 'publish',
+			)
+		);
+
+		$_POST = array(
+			'action'              => 'wp-link-ajax',
+			'_ajax_linking_nonce' => wp_create_nonce( 'internal-linking' ),
+			'search'              => 'Test Link Search',
+		);
+
+		try {
+			$this->_handleAjax( 'wp-link-ajax' );
+		} catch ( WPAjaxDieContinueException $e ) {
+			// We expect it to die after echoing JSON.
+		}
+
+		$response = json_decode( trim( $this->_last_response ), true );
+
+		$this->assertIsArray( $response );
+		$this->assertCount( 1, $response );
+		$this->assertSame( $post->ID, $response[0]['ID'] );
+		$this->assertSame( $post->post_title, $response[0]['title'] );
+	}
+
+	/**
+	 * Tests successful search using the 'term' parameter.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_wp_link_ajax_term_success(): void {
+		$post = self::factory()->post->create_and_get(
+			array(
+				'post_title'  => 'Another Test Link',
+				'post_status' => 'publish',
+			)
+		);
+
+		$_POST = array(
+			'action'              => 'wp-link-ajax',
+			'_ajax_linking_nonce' => wp_create_nonce( 'internal-linking' ),
+			'term'                => 'Another Test Link',
+		);
+
+		try {
+			$this->_handleAjax( 'wp-link-ajax' );
+		} catch ( WPAjaxDieContinueException $e ) {
+			// We expect it to die after echoing JSON.
+		}
+
+		$response = json_decode( trim( $this->_last_response ), true );
+
+		$this->assertIsArray( $response );
+		$this->assertCount( 1, $response );
+		$this->assertSame( $post->ID, $response[0]['ID'] );
+	}
+
+	/**
+	 * Tests successful search with pagination.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_wp_link_ajax_pagination(): void {
+		// Create 21 posts to ensure at least 2 pages (default is 20 per page).
+		self::factory()->post->create_many(
+			21,
+			array(
+				'post_title'  => 'Paginated Post',
+				'post_status' => 'publish',
+			)
+		);
+
+		$_POST = array(
+			'action'              => 'wp-link-ajax',
+			'_ajax_linking_nonce' => wp_create_nonce( 'internal-linking' ),
+			'search'              => 'Paginated Post',
+			'page'                => 2,
+		);
+
+		try {
+			$this->_handleAjax( 'wp-link-ajax' );
+		} catch ( WPAjaxDieContinueException $e ) {
+			// We expect it to die after echoing JSON.
+		}
+
+		$response = json_decode( trim( $this->_last_response ), true );
+
+		$this->assertIsArray( $response );
+		// On page 2, we should have 1 post.
+		$this->assertCount( 1, $response );
+	}
+
+	/**
+	 * Tests search failure due to invalid nonce.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_wp_link_ajax_invalid_nonce(): void {
+		$_POST = array(
+			'action'              => 'wp-link-ajax',
+			'_ajax_linking_nonce' => 'invalid-nonce',
+			'search'              => 'Test',
+		);
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'wp-link-ajax' );
+	}
+
+	/**
+	 * Tests behavior when no results are found.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_wp_link_ajax_no_results(): void {
+		$_POST = array(
+			'action'              => 'wp-link-ajax',
+			'_ajax_linking_nonce' => wp_create_nonce( 'internal-linking' ),
+			'search'              => 'NonExistentPostTitle',
+		);
+
+		try {
+			$this->_handleAjax( 'wp-link-ajax' );
+		} catch ( WPAjaxDieContinueException $e ) {
+			$this->assertSame( '0', $e->getMessage() );
+			return;
+		}
+
+		$this->fail( 'Expected WPAjaxDieContinueException was not thrown.' );
+	}
+}