Born in Mount Vernon, Glascow, Barrowman moved with his family to Joliet, Illinois, U.S., when he was eight. During his high school years there, he was inspired by his singer mother and encouraged by his executive father to pursue his love of music and drama. After graduation, he attended the U.S. International University in San Diego on a full music and drama scholarship. In 1989, Barrowman relocated to England to study theatre.

Barrowman is also a member of the Duke of Edinburgh Awards Scheme, an organization dedicated to promoting outstanding achievements in young people. Each year, the Duke of Edinburgh and Barrowman present the awards to exceptional youths, and the ceremony has taken the actor to Buckingham Palace and other royal venues throughout England.

John has given numerous concert performances around the world including several Royal Command Performances. John has performed on the BBC in "The Magic of the Musicals" from the Glasgow Royal Concert Hall ,in a concert version of Call Me Madam with Tyne Daly and opposite Betty Buckley on National Music Day.

Best known to American television audiences for his roles as Peter Fairchild on the series "Central Part West," and as Peter Williams on the series "Titans," John Barrowman has been working theatergoers and critics alike in London, Los Angeles, and New York for the past decade.

He recently made his cabaret debut to great critical acclaim both in Chicago and at Arci's Place in New York.

Most recently, Barrowman appeared on Broadway with Carol Burnett and Kathie Lee Gifford in Stephen Sondheim's Putting it Together, and reprised his role from the acclaimed Los Angeles produciton at the Mark Taper Forum.

He made his Broadway debut as Joe Fillis in Sunset Boulevard, opposite Betty Buckley, with whom he starred in the London re-launch at the Adelphi Theatre.

He also received a Laurence Olivier Award nomination for Best Actor in a musical in the premiere porduction of The Fix, directed by Sam Mendes (American Beauty) at the Donmar Warehouse in London.

Barrowman has been with his civil partner, Scott Gill, since 1993, after meeting during a production of Rope at the Chichester Festival Theatre. The couple have homes in London and Cardiff Bay. As Barrowman explained when the couple were interviewed by Attitude magazine, the couple do not want to call this a marriage: "We just signed the civil register. We didn't have any ceremony because I'm not a supporter of the word marriage for a gay partnership."

The two did have a small ceremony in Cardiff with around 40 friends and family on December 27, 2006.

Barrowman owns two houses in London, and currently lives in Los Angeles with his two dogs, Penny and Lewis.

John is currently playing Bobby, the lead in Stephen Sondheim's Company at the Kennedy Center as part of their 2002 Sondheim Celebration.