Haines put in supporting appearances in such films as "Circe the Enchantress" (a 1924 Mae Murray vehicle) and as an Irish cop in the Mary Pickford starrer "Little Annie Rooney" (1925) before becoming a star in his own right with "Brown of Harvard" (1926). The role established his brash, wisecracking but ultimately good-natured screen persona, which carried him through the silent era. His films were enormously popular with the public, often teaming him with either Joan Crawford ("Spring Fever", "West Point", "The Duke Steps Out") or Anita Page ("Telling the World", "Speedway", "Navy Blues"). One of his best films, and one of his best-remembered, was King Vidor's delightful comedy set in the world of Hollywood filmmaking, "Show People" (1928), in which Haines' slapstick clown teamed memorably with Marion Davies' aspiring ingenue.
Talkies gradually ended Haines' career, but not because of his voice--the brash, overwhelming character which had seemed endearing in silents was simply obnoxious with sound. He no longer looked like a college kid, and after a dozen or so unremarkable talkies he left MGM in 1932. After two B films for Mascot (both 1934), he retired from the screen to open a hugely successful interior design firm. His partner for nearly 50 years (personally and professionally) from the mid-1920s until his death was James Shields.