Mike served as an Assistant coach of the US Indoor U20 team in 2019 and the Head Coach of the U15 team in 2021 that took home a silver medal in the world games. 

In college, Mike O’Brien was a three-year starter and team captain at Hobart, one of upstate New York’s most storied lacrosse programs. After college, O’Brien signed professional lacrosse contracts in the National Lacrosse League and Professional Lacrosse League in both Minnesota and Charlotte where he suited up for the Minnesota Swarm and Charlotte Copperheads.

Mike also played for the Kitchener Waterloo Braves of the Junior A Lacrosse League in Ontario and was a two-time all-star. He is a member of the Gunnery Athletic Hall of Fame and was a US Lacrosse High School All-American, Defensive MVP, and three-year all-league selection in the New England Prep League.