When the New York run for Butterflies Are Free ended, Dirk Benedict received an offer to repeat his performance in Hawaii, opposite Barbara Rush. While there, he appeared as a guest lead on Hawaii Five-O. The producers of a psycho-thriller called Ssssss saw Benedict's performance in Hawaii-Five-O and promptly cast him as the lead in that movie. He next played the psychotic wife-beating husband of Twiggy in her American film debut W. Benedict starred in the television series, Chopper One, but his career break came in 1978 when he appeared as Lieutenant Starbuck in the movie and television series Battlestar Galactica.

Four years later, Dirk gained further popularity in what is arguably his most famous and popular role, as con-man Lieutenant Templeton "Faceman" Peck in 1980s action television series, The A-Team. He did not appear in the pilot film; creators Stephen J. Cannell and Frank Lupo wanted him from the beginning, but the network executives insisted that they wanted a different sort of actor in the role. Tim Dunigan won the part, but upon completion of the pilot, the executives decided that he wasn't quite right for the role, and it was given to Benedict after all. He played this high profile role from 1982 to 1986 (although the series didn't air until January 1983, and the final episode wasn't shown until 1987 reruns).

In 1987, Benedict took the title role of Shakespeare's Hamlet at the Abbey Theatre. In 2000, Benedict wrote and directed his first screenplay, Cahoots. In 2005, he played a role in the German movie Goldene Zeiten (Times of Gold) by Peter Thorward, portraying an 80s movie star attempting to make a comeback.

Dirk appeared as a contestant on the controversial fifth UK series of Celebrity Big Brother, broadcast in the UK. Bookmakers gave him the third-best odds of winning out of the 14 contestants. He made what is possibly the show's most memorable entrance to date, arriving in the classic A-Team van (although this was a replica, not an original, as it sported a red instead of tan interior), accompanied by the famous theme tune. He also smoked a cigar on his entrance to the house, and claimed to a fellow housemate to have a whole stock of cigars in his luggage, telling Big Brother producers "no cigars, no Benedict" as part of the deal to appear on the show. Dirk was the third-to-last contestant to be evicted from Celebrity Big Brother, finishing in third place overall with 16% of the public vote. All three remaining contestants were non-Brits.