During his three-year course at the London Academy of Music and Dramatic Art (LAMDA), James D'Arcy acted in several plays, like "Heracles", "As You Like It", "Wild Honey", "The Freedom of the City" and "Sherlock Holmes". In 1996, just a year after graduating from the institution, he started off his acting career with small roles on the TV series "Silent Witness", "Dalziel and Pascoe", and "Brookside". The following year, he starred in two TV films; "The Canterville Ghost" and "The Ice House", TV series "Ruth Rendell Mysteries", "A Dance to the Music of Time", and "The History of Tom Jones, a Foundling", in addition to appearing in movie "Wilde".

In the next few years, D'Arcy kept adding TV films into his resume, naming some were "The Life and Adventures of Nicholas Nickleby", "Sir Gawain and the Green Knight", and "Sherlock: Case of Evil". Beginning from early 2000, he frequently appeared on TV series, including "P.O.W", "Agatha Christie's Poirot", "Agatha Christie's Marple", "Ancient Rome: The Rise and Fall of an Empire", "The Inspector Lynley Mysteries", "Bonekickers", and "Secret Diary of a Call Girl".

Among the big screen features D'Arcy had starred in were "Guest House Paradiso", "Revelation", "dot the i", "Master and Commander: The Far Side of the World", "Exorcist: The Beginning", "An American Haunting", and "Rise". He, moreover, also acted in "Age of Heroes", "W.E.", "In Their Skin", "Cloud Atlas", "Hitchcock", "Let's Be Cops", also "Agent Carter".

D'Arcy was born Simon D'Arcy on August 24, 1975 in Fulham, London. Back in 2002, he was nominated for the Ian Charleson Award for the category of Outstanding Performance in a Classical Role for his involvement in play "Edward II".