In 2008, Quillin defeated Dionisio Miranda by unanimous decision at the Hard Rock in New York City, which helped him to begin working with trainer, Freddie Roach. Quillin moved from New York to Los Angeles in 2010 to train with Roach and by 2011 went on to fight and stop title contender Jesse Brinkley, which was the win that landed him in the vacant US Boxing Organization Super Middleweight Championship. Later that same year, he beat LeHoullier cleanly by points, and made an impressive HBO debut by stopping Craig McEwan in the sixth round. In 2012, Quillin fought Winky Wright and won by unanimous decision causing Wright to retire. He is currently undefeated and rumored to be fighting Floyd Mayweather in 2014.