Ewing's first television appearance was in 1964 as Marvin Grogan on ABC's sitcom Bewitched in the episode "The Girl Reporter". He also appeared that season as Eddie Fox in the episode "The Christmas Show" of ABC's short-lived The Bing Crosby Show, starring Bing Crosby and Beverly Garland, and in a third sitcom as well in the role of Norman in the episode entitled "Look Who's a Sailor" on CBS's short-lived The Baileys of Balboa.
In 1965, Ewing, at twenty-three, appeared as Private Swensholm in the World War II film None but the Brave starring Frank Sinatra and Clint Walker. That same year, he appeared as Billy Wallace in the episode "The Calf Women" of CBS's western Rawhide starring Eric Fleming and Clint Eastwood.
After his Gunsmoke role ended, Ewing appeared in two films: as Donald Maxwell in the western production Smith! starring Glenn Ford (1969) and as Nelson in Play It As It Lays, a psychiatric drama starring Tuesday Weld and Anthony Perkins (1972). Also in 1969, Ewing was a Celebrity contestant on an episode of The Dating Game in which the eligible bachelorette was Future Actress Lindsay Wagner.
