Prior to Friday's game at Stade des Costieres, Cornet has been in impressive form in front of goal having scored four goals in his last four league outings.
The Ivorian forward opened the scoring in the sixth minute but Nimes fought back to grab a 2-1 lead in the first half.
Towards the end of the encounter, Cornet inspired the Kids' comeback with his second effort of the night in the 89th minute before Tanguy Ndombele scored the match-winning goal in stoppage time.
The victory ensured that Lyon finished their 2018-19 campaign in third place with 72 points after 28 games. They also secured progress to the qualification round of next season's Uefa Champions League.