Hart attended his first Brier in 1995 as an alternate for Ed Werenich. It was his only major tournament experience before winning the 1997 Canadian Olympic trials as the third for the Mike Harris team. At the 1998 Winter Olympics, the team won a silver medal. He left the team in 2000, and joined up with Glenn Howard. Eventually with Howard, Hart would go to another Brier, in 2006 where they lost in the final. The following year, they won the 2007 Tim Hortons Brier and then the 2007 Ford World Men's Curling Championship. As vice with Glenn Howard he placed 2nd in the Olympic trials in Edmonton in 2010 and is a runner up for the past 3 Briers. He is nicknamed "the Hart Surgeon" for his ability to make difficult shots under pressure. He was the 2011 winner of the annual Ford Hot Shots skills and shot-making competition that precedes the start of play at the Brier.