"Nice found an agreement with Claude Puel who will be the club's head coach for the next three years," the club said on their website.
Puel, 50, will be introduced on Thursday.
He was sacked last June after a three-year spell at Lyon, where he failed to win a single trophy despite joining the club when they were defending French champion in 2008.
He, however, led Lyon to their first Champions League semi-final in 2010.
Puel started his coaching career at Monaco where he won the French title in 2000 before spending six years as Lille's manager.