David Ackroyd extended his all-stage career into film and television in the early 1970s, beginning with daytime leading man outings in The Secret Storm and Another World. He progressed to prime time work as Gary Ewing in Dallas until Ted Shackelford successfully took over the role when the character moved front and center with the spin-off drama Knots Landing, though Ackroyd himself would later appear on Knots Landing as a guest star, playing a different character. Coincidentally, Shackelford's last recurring role prior to Dallas was on Another World. David's prime on-camera work occurred in the late 1970s with a series of strong co-star roles in the miniseries The Dark Secret of Harvest Home as Nick Constantine; The Word and the TV-movies And I Alone Survived, Exo-Man and Women in White. He also costarred in the short-lived series AfterMASH and A Peaceable Kingdom.

On Broadway, Ackroyd appeared in Unlikely Heroes, a 1971 production of three plays based on the stories of Philip Roth; and Children of a Lesser God, in which he replaced John Rubinstein as the lead character, James Leeds, in 1981. Since the late 1990s and into the 2000s, Ackroyd has narrated documentary television series like History's Mysteries and UFO Files: "Alien Engineering".

Ackroyd moved to Montana in 1996 and in 2003 co-founded Alpine Theatre Project in Whitefish, a professional acting company which has featured appearances by such notable performers as Olympia Dukakis, John Lithgow and Kelli O'Hara. He is the company's Artistic Development Director.