The Eagles have been looking for a new man to lead the side ever since Oliver Glasner confirmed he would be leaving the club back in January.
Glasner was a fan favourite in South London after bringing Palace their first-ever pieces of silverware, winning the FA Cup, Community Shield and UEFA Conference League.
Sage is also no stranger to winning trophies; the Frenchman guided Lens to their first-ever Coupe de France last season on top of a second-placed finish in Ligue 1.
In his 40 games in charge of the club, Sage won 27, drew five and lost eight. He will begin as Palace manager on July 1st, with the club set for their first foray into Europa League football.
The 47-year-old's first stint in management came in 2013 with amateur club Chambery before a decade-long break saw Sage return to coaching with Lyon in 2023.
Initially only an interim boss, he became permanent manager in January 2024 but was sacked just over a year later following a run of bad results.