He rose to prominence portraying U.S. Army Major Richard Winters in the HBO miniseries Band of Brothers.

He portrayed Bobby Axelrod in the Showtime series Billions in six out of seven seasons, and appeared in Once Upon a Time in Hollywood (2019) as actor Steve McQueen.

[8] Lewis has said that he "went to English boarding schools and grew up around people very much like [his character] Soames and in a milieu very much like the Forsytes'".

[13] His first television appearance was as a medical student in "Hickory Dickory Dock", a feature-length episode of Agatha Christie's Poirot, an ITV Studios TV production, broadcast in 1995.

This production was seen by Steven Spielberg, who later cast Lewis as Richard Winters in Band of Brothers (2001), the first role of several that required him to have a credible American accent.

[10] On the heels of this role, he starred in Keane as a Manhattanite with a fragile mental state who is searching for his missing daughter.

Since 2004, he has appeared in a number of films, as well as the 2005 BBC TV adaptation of the Shakespeare comedy Much Ado About Nothing, as part of the ShakespeaRe-Told season.

[21][22][23] In 2008, Lewis starred as the main character Charlie Crews in the American television series Life on NBC.

[28] Lewis played Tory Prime Minister Simon Laity in two seasons of Number 10 on BBC Radio 4.

[31] From 2011 to 2013, Lewis had a starring role as Gunnery Sergeant Nicholas Brody in the Showtime series Homeland, for which he won a Primetime Emmy Award.

[33] In 2016 he began starring as billionaire hedge fund manager Bobby Axelrod in the Showtime series Billions.

[42][43] It features personal reflections by 36 celebrities as well as four ordinary people helped by The Prince's Trust,[44] about musical lyrics that inspired them.

[53][54] Lewis' portrayal of U.S. Army Major Richard Winters in the HBO miniseries Band of Brothers earned him a Golden Globe nomination.

[59][60] Having previously dated Katie Razzall, Kristin Davis, and Sophia Myles,[61] Lewis married actress Helen McCrory on 4 July 2007.