Redirect User Registration to Custom Registration Page

redirect_registration_page.php

<?php
// Redirect Registration Page
function my_registration_page_redirect()
{
	global $pagenow;

	if ( ( strtolower($pagenow) == 'wp-login.php') && ( strtolower( $_GET['action']) == 'register' ) ) {
		wp_redirect( home_url('/registration-url'));
	}
}

add_filter( 'init', 'my_registration_page_redirect' );