[2] O'Brien earned an appointment to the United States Naval Academy, where he was a three-year starter at defensive end for the Midshipmen from 1968 to 1970.

During this time he began coaching as an assistant for Navy's plebe (freshman) team, then served at the Marine base in Quantico, Virginia, as well as tours of duty in California and Japan.

[4] In 1999, three years of hard work paid off for O'Brien, his staff and players as they engineered the third-best turnaround in Division I college football.

Led by Minnesota Vikings' first-round draft pick and All-American Chris Hovan, the Eagles registered three consecutive wins over Syracuse, West Virginia and Notre Dame to finish the regular season with an 8–3 record, a top 25 national ranking and a trip to the Insight.com Bowl - Boston College's first bowl appearance since 1994.

[4] The 2001 season was a satisfying one for O'Brien as the Eagles finished 8–4 and ranked in the top 25 in both major polls, capped by a 20–16 win over SEC powerhouse Georgia in the Music City Bowl.

Boston College gave eventual national champion Miami by far its biggest scare of the entire season at Alumni Stadium as the Hurricanes were able to pull out a victory only in the final seconds.

Running back William Green rushed for 1,559 yards and was the second-leading rusher in the country and a consensus first-team All-America pick.

His freshman quarterback, future NCAA All-American and NFL star Russell Wilson, became the first rookie in the history of the Atlantic Coast Conference to be named first-team all-conference at his position and it marked the sixth time in his 19 years in the league that a quarterback under O'Brien's tutelage was named the All-ACC signal caller.

With the Champs Sports Bowl victory over West Virginia, the 2010 squad tied the second highest win total in school history while finishing 9–4.

[7] In 2011, after a brief stint in minor league baseball that caused him to miss spring practice, Russell Wilson transferred to Wisconsin for his final year of eligibility after O'Brien named Mike Glennon as his quarterback for the 2011 season.

On November 25, 2012, O'Brien received notice from NC State that he had been dismissed effective immediately after navigating the team to a 7–5 regular-season record.

O'Brien's recruiting classes were frequently in the bottom half of the nation, and Yow wanted a coach who could bring top 25-type talent to Raleigh.

[11] O'Brien is active in community outreach programs and serves on the board of directors for the Marine Corps' "Toys for Tots."