O'Brien initially played college soccer for the University of San Diego, where he was an NSCAA Freshman All-American and was named to the All-WCC Second Team, before transferring to UC Santa Barbara in his sophomore year.

During his college years, O'Brien also played for Tacoma Tide of the USL Premier Development League, where his father was head coach.

O'Brien was sent on loan to USL First Division side, Seattle Sounders, in August 2008 to gain first team experience.

During summer 2010, O'Brien trialed with League of Ireland Premier Division side Sporting Fingal but a loan deal with Colorado could not be agreed.

[8] O'Brien was named as an assistant coach of the UC Santa Barbara Gauchos men's soccer team in August 2015.