Dupuis began playing tennis at the age of nine with his father Xavier. He mentioned in an interview once that he prefers clay and hard court surfaces. He was coached by Benoit Carelli, whom he credits with improving his physical and mental ability. Carelli had coached Dupuis since February 1998.
Dupuis won one singles title in Milan in 2004 and reached a career-high singles ranking of World No. 57 in September 2001.In 2006 he tested positive for the banned drugSalbutamol and was suspended for two and a half months.