Cape Verde international Tavares has been at the club since 2012, joining from rivals Bourg-Peronnas, and he has been a regular first-team fixture, making 173 appearances across all competitions, scoring 55 goals.
The 28-year-old's current contract was due to expire in nine months, leading to doubts over his future, but he has now signed a new deal that will keep him at the Stade Gaston Gerard until 2021.
Delcourt has expressed his delight at being able to tie the striker down for the foreseeable future and is adamant Tavares will continue to be a big player for the team.
"This contract extension rewards a player who has always had an irreproachable state of mind and a real attachment for his club," he said. "Like Dijon, he has always managed to successfully cross the ladder to Ligue 1. An example for all, which embodies the values of the club."