Malahide often alternates between strict authority figures and sleazy villains. He had a running role on the comedic crime drama Minder as the suspicious foil Detective Sergeant Chisholm (1979-1988). He appeared in several miniseries, both period and modern, notably The Singing Detective (opposite Michael Gambon, as adversary Binney), The Pickwick Papers (Mr. Jingle), and Middlemarch (Rev. Casaubon). He starred as Chief Inspector Roderick Alleyn in Alleyn Mysteries (from the Ngaio Marsh novels), while later roles include Lord Glendenning on the first season of The Paradise and arch criminal Jack Turner on Hunted. Most recently, he appeared in four episodes of Game of Thrones as Balon Greyjoy and was a regular on Indian Summers as Lord Willingdon.
In film, Malahide played the skeptical ballet school principal in Billy Elliot and appeared in Quills, The World Is Not Enough, Sahara, U.S. Marshals, The Long Kiss Goodnight (with Geena Davis and Samuel L. Jackson), The Killing Fields (with Sam Waterston), EuroTrip, Captain Corelli's Mandolin, and Brideshead Revisited. Guest appearances include Blackadder (as Guy of Glastonbury in the first series' finale), Extras, Poirot, Lovejoy, Inspector Morse, The New Avengers, and Danger UXB.