Methods of forming a coating system (18) on a surface (13) of a cobalt-based superalloy component (5) are provided. The method includes forming a nickel-based primer layer (20) on the surface (13) of the cobalt-based superalloy component (5); forming an intermediate nickel-containing layer (30) on the nickel-based primer layer (20), wherein the intermediate nickel-containing layer (30) comprises a nickel, chromium, and aluminum; forming an aluminide layer (34) on the intermediate nickel-containing layer (30); and heat treating the cobalt-based superalloy component (5) to form a diffusion coating (40) on the surface (13) of the cobalt-based superalloy component (5). Coated cobalt-based superalloy component (5)s formed from such a method are also provided.