Born in Port-of-Spain, Boldon left for the United States at age fourteen, and became a football player. There, his sprinting capacities were discovered, and he quit playing football in the early 1990s.
Boldon was sent to represent Trinidad and Tobago at the 1992 Summer Olympics in Barcelona, and later that year he won the 100 m and 200 m titles at the World Junior Championships.
Boldon won his first international medal at the 1995 World Championships, taking home the bronze in the 100 m. He repeats that performance at the 1996 Summer Olympics, where he also places third in the 200 m. In 1997, he wins his first title, taking the 200 m at the World Championships, his country's first title in that competition.
A silver medal in the 100 m and a bronze in the 200 m were the result of the 2000 Summer Olympics, after he had been hampered by injuries the year before.
In 2001, Boldon tested positive for ephedrine, and was given a warning, but was not suspended. Boldon maintained the doping was part of a cold medicine.