Justin studied musical theatre at the Chicago Academy for the Arts from 1994–98. While at the Chicago Academy for the Arts, he started an annual AIDS Benefit.
After graduation from The Academy, Tranter moved to Boston to study at the Berklee College of Music. Along with songwriting, he also took classes in business management, in preparation for a career in music. Tranter graduated from Berklee in three years, with a GPA of 3.9 and a degree in songwriting. While at Berklee, Justin founded Musicians With a Mission, a scholarship fund for LGBT youth education.
In 2004, Tranter joined forces with fellow Berklee graduates to form Semi Precious Weapons. He and Semi Precious Weapons opened for Lady Gaga on her Monster Ball from 11/09-5/11. In January 2008 they caused a stir in the United Kingdom after Kate Moss attended their concert at London's Death Disco club and danced with 'six foot bisexual' singer Justin Tranter. Vogue described the band as "unashamedly crass and deliciously animated"