While still at UCLA he had the lead role in Johnny Moccasin (1956), a half hour film made for television by Laslo Benedek as a white boy raised by Indians after a massacre.

[2] He appeared on television in Chevron Hall of Stars ("Flowers for Charlie McDaniels"), The George Burns and Gracie Allen Show ("Return to California", "George's Gray Suit", "Fighting for Happiness"), Conflict ("No Man's Road" with Gig Young and Dennis Hopper), Studio One in Hollywood ("Babe in the Woods" – The New York Times said that "his playing was not too resourceful"[3]), Sergeant Preston of the Yukon ("The Criminal Collie"), and Kraft Theatre ("The Last of the Belles").

He made Trooper Hook (1957) and Gunsight Ridge (1957) with his father and was one of several young names in Lafayette Escadrille (1958) and The Restless Years (1958).

[5] McCrea had a small role in All Hands on Deck (1961) and could be seen in the episode, "The Wrestler" on the ABC situation comedy, Guestward Ho!, starring Joanne Dru.

[7] McCrea was cast as Lieutenant (later General) John J. Pershing in the 1962 episode, "To Walk with Greatness", on the syndicated television anthology series, Death Valley Days.

McCrea had a supporting role in Operation Bikini (1963) at American International Pictures starring Tab Hunter and Frankie Avalon.

He impressed the studio enough for them to cast him in a comedic role as dumb-minded Deadhead (Bonehead) in Beach Party (1963), starring Avalon and Annette Funicello.

[9] McCrea was an avid body builder, and the only actor appearing in the American International Pictures beach movies who could surf.

McCrea played the Big Lunk in the 1964 film Pajama Party, with Tommy Kirk and Annette Funicello in the lead parts.

McCrea had a small part in Young Fury (1965) and played Lieutenant Brannin, a cocky cavalry officer based loosely on George Armstrong Custer, in Sam Peckinpah's Major Dundee (1965), but his scene was deleted from the final cut.