Cawthorn made his stage debut in 1872 at the age of four. At nine, he went to England and played in music halls for four years. In 1898, Cawthorn made his debut on Broadway and carried on a successful career for some twenty-five years. Moving to Hollywood in 1927, he began a career as a character actor. Married to stage and screen actress Queenie Vassar, Cawthorn passed away following a stroke in his Beverly Hills home.