He was Shaun Pianta's guide at the 2018 Winter Paralympics.

O'Sullivan was born and raised in Bright, Victoria.

[1] Prior to Pianta, O'Sullivan was guide to Jessica Gallagher and Prue Watt.

[1] At the 2016/17 World Para-alpine skiing Europa Cup event in Veysonnaz, Switzerland, in their first major international competition, Pianta and O'Sullivan posted career-best scores in the men's Super G and giant slalom.

[1] At the 2018 Winter Paralympics, Pianta and O'Sullivan competed in two events - 14th in the men's giant slalom visually impaired and did not finish in the men's slalom visually impaired.