Invoke colorbox from a URL (not a link)
You should use java-script and the iframe support in color-box.

&lt;script type="text/javascript"&gt;
  $(document).ready(function() {
    $("a", ".the-class-added-to-links-clicking-which-will-open-theurl-in-coloyxbox").click(
      function(event) {
        event.preventDefault();
        var elementURL = $(this).attr("href");
        $.colorbox({iframe: true, href: elementURL, innerWidth: 645, innerHeight: 509});
      });
  });
&lt;/script&gt;


Code Source : https://stackoverflow.com/a/8933655/493742