O'Brien's discography is generally diverse yet also maintains a notable background and standing in the hard rock and metal music genres.

O'Brien's live credits include tours with bands such as Disturbed,[1] Tommy Lee, Static-X, Methods of Mayhem, Lita Ford, Daughtry, and Steven Adler, among others.

Also a busy session-bassist, most of this work taking place in his current home base of Los Angeles, O'Brien has recorded with numerous artists such as Celine Dion, Chris Cornell, Brian McKnight, Tommy Lee, Jason C. Miller, Lindsay Lohan, Gus G., Lita Ford, and Kelly Clarkson.

O'Brien spent two months playing bass for Disturbed on an extensive tour throughout Europe, opening for Marilyn Manson.

Over the next few years, O'Brien quickly accumulated an impressive resume of artists that he has recorded with, such as Celine Dion, Chris Cornell, Brian McKnight, Mýa, Tommy Lee, Lindsay Lohan, and Kelly Clarkson, including her number-one single, "Because of You", on the grammy-award-winning album, Breakaway.

The band was launched on June 22, 2009, at a press conference in Hollywood, California, and soon signed a deal with Universal Republic Records.