An editor in the late '30s, Keller began directing in 1949 with The Blonde Bandit. Over the next two decades he helmed numerous low-budget films, mostly actioners and romantic comedies. His notable efforts include the alcoholism drama Voice in the Mirror and the Audie Murphy westerns Seven Ways from Sundown and Six Black Horses. Keller began producing films in the mid '60s, and made such memorable films as Kitten with a Whip starring Ann-Margret; director Norman Jewison's farce Send Me No Flowers, with Rock Hudson and Doris Day; and the comic western Skin Game. In the late '60s Keller turned his attention to television, but returned to editing in the late '70s and early '80s, cutting the Bill Murray comedy Stripes and director Sidney Poitier's Stir Crazy, Hanky Panky, and Fast Forward.