During school, Devine acted in various amateur and school productions. She migrated to New Zealand with her family when she was six years old and competed in Irish dance during her teens. In 1994, Katrina earned a role on Shortland Street, which she appeared in for eight years playing receptionist Minnie Crozier. In 1998, she won the best supporting Actress award at the New Zealand Television Awards for her work on the show.
Later, in 2001, Devine married former Shortland Street co-star Blair Strang; the couple later divorced. In 2003, Katrina played the villainous Marah on Power Rangers Ninja Storm, and later returned to play the recurring role of Cassidy on Power Rangers Dino Thunder in 2004.
