John Barrowman was born in Scotland, and moved to Illinois when he was eight years old. He is bi-dialectal, doing much of his stage and acting work in his American accent, but speaking with family in his Scottish accent.

He moved back to Britain in 1989 when he was hired to play the lead in Anything Goes. He took on a number of West End roles, including the leads in Sunset Boulevard and Miss Saigon and a dramatic play entitled Rope, while working as a children's television presenter and came back to America briefly to work on short lived shows such as Central Park West and Titans. He then bounced around Broadway, West End and the LA Stage for a number of years before moving back to Britain permanently. He won the role of Captain Jack Harkness in the new Doctor Who series and went on to star as Captain Jack in its adult spin-off Torchwood.

John married Scott Gill, his partner of fifteen years, in December 2006.