The 20-year-old Kouame clocked 32.835 seconds - the only rider under 33 seconds - to finish ahead of Germany's Emma Hinze, who had the best time in the qualifications.
China's Yufang Guo took third place.
No Frenchwoman had won the 500m title since Felicia Ballanger in 1999 in Berlin.
Kouame's triumph came a day after compatriot Mathilde Gros stunned the mighty Germans in the individual sprint.