The Ineos-owned Nice announced on Wednesday they had appointed Olivier Pantaloni as coach weeks after avoiding relegation from Ligue 1.
Frenchman Pantaloni, 59, replaces ex-Southampton boss Claude Puel who helped the southerners retain their top-flight status with a play-off win over Ligue 2's Saint-Etienne on May 29.
Pantaloni, who spent three years in Nice's youth set-up in the 1980s without playing a first-team game, left Lorient at the end of the season.
He had guided them into Ligue 1 in 2025 before a 10th placed finish in the table.
"I am delighted today to be returning to the south of France and to a club I know well, having played here for a time," Pantaloni said in a club statement.
"It is up to us to live up to the supporters' expectations and restore OGC Nice to its former glory," he added.
Pantaloni arrives at the four-time French champions in disarray. They have a new president, Maurice Cohen, but are without a director of football after Florian Maurice's departure in June.
British entrepreneur Jim Ratcliffe's Ineos bought the Cote d'Azur club in 2019. He also has a stake in Manchester United and is looking to sell the French side.
Ineos have held talks with an American investment fund in recent months.
This summer, Les Aiglons have already sold Ivory Coast winger Jeremie Boga to Juventus. According to club sources Belgian midfielder Charles Vanhoutte is a nearing a move to Feyenoord.
Nice start the new Ligue 1 season against Pantaloni's former club Lorient on the weekend of August 22-23.
