Cumming was born the son of Mary, an insurance company secretary, and Alex Cumming, a forester. He has one older brother, Tom.

Cumming attended Monikie Primary School and Carnoustie High School and originally aspired to a career in veterinary medicine; but a personality clash with his biology teacher put him off the idea and he subsequently set his sights on becoming an actor.

Following graduation, he spent a year and a half employed as an editor for the Scottish pop magazine TOPS before entering the Royal Scottish Academy of Music and Drama.

Cumming is a Scottish film and stage actor, perhaps best known for his supporting roles as Boris Grishenko in the James Bond film GoldenEye, Kurt Wagner/Nightcrawler in X2: X-Men United and on the stage with his Tony Award-winning lead performance as the Emcee in the highly successful revival of Cabaret.

He has directed, produced, and written films, TV series and plays, voiced several soundtracks, written a book, developed a stand-up show at the Edinburgh Fringe, and formed his own production company.