He appeared in many westerns, such as Hondo, The Young Guns, The Burning Hills, The Wild Bunch, Fort Massacre, and Cahill U.S. Marshal. He also appeared in the 1955 comedy Bowery to Bagdad. Barnes' television appearances included most notably The Life and Legend of Wyatt Earp in which he portrayed Ike Clanton. Other series he appeared on include Father Knows Best, Highway Patrol, The Untouchables, Cheyenne, Maverick, Have Gun - Will Travel, The Twilight Zone, The Big Valley, Daniel Boone (starring Peter Bromilow), The High Chaparral, Bonanza, Gunsmoke, Wonder Woman, Little House on the Prairie, Fantasy Island, The Dukes of Hazzard, and Walker, Texas Ranger (starring Bill Bolender and featuring Jeff Mack). His final role was on the NBC medical drama ER (featuring Jeff Mack, Michael Hissrich and Kevin Scott).
Barnes lived in Santa Monica, California, with his partner, Debbie. He had a younger brother, Lou Dupont, who was a ventriloquist. Barnes died in Santa Monica, California on 11 November 2000, at the age of 80.