Redirect to a hash from the controller using "RedirectToAction"

I found this way:

public ActionResult MyAction(int id)
{
    return new RedirectResult(Url.Action("Index") + "#region");
}

You can also use this verbose way:

var url = UrlHelper.GenerateUrl(
    null,
    "Index",
    "DefaultController",
    null,
    null,
    "region",
    null,
    null,
    Url.RequestContext,
    false
);
return Redirect(url);

http://msdn.microsoft.com/en-us/library/ee703653.aspx

Great answer gdoron. Here's another way that I use (just to add to the available solutions here).

return Redirect(String.Format("{0}#{1}", Url.RouteUrl(new { controller = "MyController", action = "Index" }), "anchor_hash");

Obviously, with gdoron's answer this could be made a cleaner with the following in this simple case;

return new RedirectResult(Url.Action("Index") + "#anchor_hash");

A simple way in dot net core

public IActionResult MyAction(int id)
{
    return RedirectToAction("Index", "default", "region");
}

The above yields /default/index#region. The 3rd parameter is fragment which it adds after a #.

Microsoft docs - ControllerBase