He was the son of the singing cowboy star Tex Ritter and the father of actors Jason and Tyler Ritter. Ritter is known for playing Jack Tripper on the ABC sitcom Three's Company (1977–1984), for which he received a Primetime Emmy Award and a Golden Globe Award in 1984. He briefly reprised the role on the spin-off Three's a Crowd, which aired for one season.
Ritter appeared in over 100 films and television series combined and performed on Broadway, with roles including adult Ben Hanscom in It (1990), Problem Child (1990), Problem Child 2 (1991), and Bad Santa in 2003 (his final live action film, which was dedicated to his memory). In 2002, Don Knotts called Ritter the "greatest physical comedian on the planet"