Domenico Fioravanti was born at Novara, Piedmont. He started to swim competitively at the age of nine, and one year later began training daily, spurred by his elder brother Massimiliano who was also a swimmer. In 1995 he took part at his first European Championship. In 1999 he was European champion in the 100 m breaststroke.
In 2000 Fioravanti became the first Italian swimmer to win a gold medal in the Olympic Games, winning both the 100 m and 200 m breaststroke races. He also won another gold European medal in the 100 m breaststroke. In 2001 he received the silver medal in the 100 m breaststroke and bronze medal in the 50 m breaststroke at the World Championship. Moreover, he won the Italian championship thirty times. In 2004 he was forced to retire from competitive swimming due to a genetic heart anomaly.