The 22-year old, who won gold at Atlanta in the 1 kilometre event, beat American Marty Nothstein in both rounds of the final.
Australian Darryn Hill, who was world champion in the event in 1994, took third place.
Rousseau has previously won two world championships in the 1 km race and is the first Frenchman since Daniel Morelon in 1975 to win the prestigious sprint title.
Franco-American Marion Clignet scored a career second world title in the women's pursuit when she outclassed Australian Lucy Tyler-Sharman.
The 32-year old, who was born in the United States to French parents, was only five-hundreths of a second outside her world record, clocking 3min 31.023sec.
Despite suffering from epilepsy, which prevents her from being able to drive a car, the determined Frenchwoman has been a consistent performer in the pursuit event, claiming the world title for the first time in 1994.
Earlier in the day, Spaniard Juan Llaneras rode to his first ever world championship victory here, winning the 40km points race after a down-to-the-wire battle with Denmark's Michael Sandstod.
The two cyclists finished the 160 laps with the same number of points, but Llaneras was given the victory on the basis of sprints won during the race.
Italian Silvio Martinello, who won gold at Atlanta in the event, took third place.
Although he started strongly and won six of the 20 sprint stages, Martinello fell victim to a strong attack from the Llaneras and Sandstod, who lapped him in the first quarter of the race.