 O'Sullivan never played football for Kerry in the All-Ireland Minor Football Championship.However, he was part of the Kerry Vocational Schools team that won the All Ireland in 1997.He moved on to the Under 21 team in 1998 lining out at Full Back in the Munster semi final game with Clare, a game Kerry ran out winnings in a close game on a 0-10 to 0-07 scoreline.