The 58-year-old Oscar winner will play Catherine, the mom of a man (Elijah Wood)who forms a special bond with his neighbor's dog. He sees the dog as a man in a dog suit.
Steenburgen joins previously announced guest stars including Chris Klein and Rashida Jones. Steenburgen recently starred in another FX project, the hour-long drama Outlaw Country and also recurs on Curb Your Enthusiasm.
Wilfred, based on the Australian series of the same name, debuts in June on FX.