"Billy's not done yet. #Goliath will return for its fourth and final season to @PrimeVideo," the streaming service tweeted Thursday.
The show casts Thornton as Billy McBride, a former successful defense attorney trying to rebuild his life and career after a murder suspect he got acquitted went on to kill a family.
He now focuses on helping clients who take on the rich and powerful.
Season 3 began streaming on Amazon last month.