Here is a list of O'Sullivan's best fights. For a list of O'Sullivan's losses, refer to "Gary O'Sullivan Losses".
On June 25, 2011 Gary O'Sullivan faced off against Robert Long in a middleweight bout at age 26. He was coming in with a record of 13-0 (9). O'Sullivan stopped Robert Long via TKO.
On March 14, 2015 Gary O'Sullivan faced off against Milton Núñez at age 30. He was coming in with a record of 20-1 (13), and Núñez was 35 years old and with a record of 28-12-1 (25). O'Sullivan stopped Milton Núñez via TKO.
