Niakhaté began his professional football career at FC Metz in 2014, where he progressed through the youth ranks before making his first-team debut in 2016. The talented defender quickly established himself as a key player for the club, helping them achieve promotion to Ligue 1 in the 2018-2019 season. Niakhaté’s impressive performances in the French top-flight caught the attention of several European clubs, and he eventually signed for Mainz 05 in the Bundesliga in 2019.