Lintern studied English Literature at Durham University as a member of Van Mildert College, graduating with a 2:1 degree in 1984. He subsequently won a scholarship to the Royal Academy of Dramatic Art.

He played a young Muhammad Ali Jinnah in the 1998 film Jinnah, and an American Cop in the 1998 film Lost Souls. He starred in the 2007 gay drama film by Channel 4 Clapham Junction, where he plays Will who is entering a civil partnership with Gavin. He was also in The Bank Job in 2008 playing an MI5 officer ordered to retrieve the embarrassing proceeds of a bank robbery in 1970s London. Other films include Syriana, Page Eight, Jinnah, Malaventura, The Calling. Lintern also had a major role in the third series of the television drama, The House of Eliott. In 2011 he had a major role in the BBC series The Shadow Line. In 2012 he appeared in Hunted for BBC One and HBO. He played Hector Stokes. He plays Thomas Chamberlain, the head of the Lyell Centre in The BBC series Silent Witness.

He has an extensive stage career, spending most professional time in the West End and the Royal National Theatre. He has appeared all over the UK, including leading roles at the Royal National Theatre, the Royal Shakespeare Company, the Royal Court Theatre <The Merchant of Venice at the West Yorkshire Playhouse and Hamlet at the Bristol Old Vic. As well as many TV shows, including Lead Balloon, Screenplay, The Beggar Bride, Covington Cross, Midsomer Murders, Cadfael, Lewis, She's Out, Demob, The Storyteller, Victoria Wood, The Line of Beauty, Forever Green, The Good Guys, The Bill, Casualty, Plotlands, Heartbeat, Performance, Holding the Baby, Bloodlines: Legacy of a Lord  is loosely based on the life and disappearance of Lord Lucan., Taggart, The Inspector Lynley Mysteries and Agatha Christie's Poirot.