O'Brien was born in Minneapolis, Minnesota, and at the age of 12, moved to Kernersville, North Carolina, where he attended East Forsyth High School.

[1] Rivals.com rated him a three-star college prospect and ranked him the 36th best quarterback in the nation and 35th best player in the state of North Carolina.

During the 2010 season, the Atlantic Coast Conference named O'Brien the ACC Rookie of the Week a total of five times.

[7] On September 20, Wisconsin head coach Bret Bielema replaced O'Brien with redshirt freshman Joel Stave, citing problems with turnovers.

[8] After Stave suffered a season-ending injury during the October 27 game against the Michigan State Spartans, O'Brien remained the backup behind fifth-year senior Curt Phillips.

[12] O'Brien also played in the 2014 Medal of Honor Bowl, a postseason all-star game, passing for 87 yards (5-for-11) and rushing for a touchdown.

A season-ending injury to second-string quarterback Thomas DeMarco allowed O'Brien to see action during the 2014 CFL season.

After winning the Grey Cup with the Redblacks in 2016, O'Brien signed with Edmonton Eskimos for the 2017 CFL season, reuniting him with former offensive coordinator and Edmonton Head Coach Jason Maas, and replacing the retired Jordan Lynch as the third quarterback, as well as holder for convert kicks and field goals.

[20] On August 11, 2018, O'Brien completed his first pass in nearly two years, on a fake field goal to defensive tackle Almondo Sewell.

After going 15 of 26 for 93 yards in two preseason games to begin the 2019 season, and failing to produce a scoring drive, Logan Kilgore won the backup job and O'Brien was released.