How do I resolve a path relative to an ASP.NET MVC 4 application root?

To get the absolute path use this:

String path = HttpContext.Current.Server.MapPath("~/Data/data.html");

EDIT:

To get the Controller’s Context remove .Current from the above line. By using HttpContext by itself it’s easier to Test because it’s based on the Controller’s Context therefore more localized.

I realize now that I dislike how Server.MapPath works (internally eventually calls HostingEnvironment.MapPath) So I now recommend to always use HostingEnvironment.MapPath because its static and not dependent on the context unless of course you want that…