The 21 year old was initially declared brain dead after being pulled out of the river by divers on Monday after he and three friends entered the river near Lyon to escape the blistering heat in France.
Guingamp paid tribute to Kies on X, writing: "Guingamp has had the sorrow of learning of the death of Kenzo Kies, a young player with the club."
A Saint-Etienne also released a statement, reading: "The Green Generation is in mourning. A resident of the Robert-Herbin Sports Centre for seven years, a talented player and discreet young man appreciated by all, Kenzo Kies has lost his life in dramatic circumstances.
"Saint-Etienne extends its most sincere condolences to his loved ones as well as to those - teammates and coaches alike - who shared a piece of his journey. Kenzo, in the corridors of L'Etrat, no one will ever forget you."
The BBC report that forty people have drowned in heatwave-related deaths in France since last Thursday as a heatwave led to people swimming in rivers to cool off.
French sports minister Marina Ferrari having issued a warning against swimming in potentially dangerous areas as the death toll rises.
“Around 20 people have drowned since the start of last weekend.
“I urge people to respect the safety warnings. People go to swim in unsupervised areas during heatwaves, and it is not a trivial matter. I understand people want to go into the water to cool down. But they really have to stick to areas that are supervised.”
Kies joined second-tier Guingamp last year and featured primarily for their reserve side who mourn his loss this month.