Born in Barendrecht, De Bruijn tried several sports before settling with swimming. She debuted at the World Championships in 1991, winning a bronze medal with the 4 x 100 m relay team, with which she had already won a gold medal at European Championships.
The following year, De Bruijn made her Olympic debut at the 1992 Summer Olympics, and finished 8th in the 100 m and 4 x 100 m freestyle events. She continued to swim with the best in the next years, but was not motivated enough to compete in the 1996 Summer Olympics, and stayed home.
She immediately regretted this decision, and decided to go to the United States to train. Her return was crowned in 1999, when she won the 50 m freestyle at the World Championships.
The following year, after having swom several World Records, she competed in the 2000 Summer Olympics in Australia. She won the 50 and 100 m freestyle, and the 100 m butterfly, setting World Records in all three events. In addition, she won a silver medal with the 4 x 100 m freestyle relay team.
She confirmed her status when she won titles in the three same events at the 2001 World Championships