Andy Hallett was raised in the tiny Cape Cod village of Osterville, Massachusetts, part of the town of Barnstable. He attended Barnstable High School and then Assumption College in Worcester, Massachusetts.

He spent his early years hiding his love for singing and performing. He would lock himself in his room when his parents weren't home and belt out his favorite tunes. Hallett eventually got to live out his dream on the Joss Whedon series Angel as Lorne, a wisecracking "good demon" who runs a karaoke establishment and can read the thoughts and souls of patrons when they sing.

Hallett considered himself shy until he had a life-changing experience at a Patti LaBelle concert. She invited him on stage to sing "Lady Marmalade" with her and when he received applause and requests for photographs, he realized that show business was in his future.

After moving to Los Angeles to pursue acting, Hallett worked as a runner at a talent agency, a property manager and a personal assistant. Angel creator and executive producer Joss Whedon saw Hallett singing at a blues revue and conceived the character of Lorne. Hallett was invited to try out for the part and landed the role, his first job as an actor.

In addition to Angel, Hallett has also starred in The Enforcers, a television mini-series about young mobsters starring James Marsters, Tangi Miller and Michelle Trachtenberg, and in the independent film Chance, written by Buffy the Vampire Slayer co-star, Amber Benson.