Kelly as a young man studied to become a cartoonist, and he originally created the Weary Willie character as a cartoon figure. Later, he joined Howe's Great London Circus as a trapeze artist, and in 1923 he brought his cartoon character to life as a clown. He worked for the Sells-Floto and Hagenbeck-Wallace circuses until 1931 and then for the Cole Bros. After appearing in England with the Bertram Mills Circus in the late 1930s, Kelly joined the Ringling Bros. and Barnum & Bailey Combined Circus in 1942 and played with them until the late 1950s. Weary Willie made his motion-picture debut in The Greatest Show on Earth (1952). Kelly's autobiography, Clown, was published in 1954. He was a mascot in spring training for the Brooklyn Dodgers in 1957 and worked sporadically thereafter until the year of his death. He died in 1979 on an opening day of the Ringling Bros. and Barnum & Bailey Combined Circus.