He succeeds Christophe Pélissier, who was dismissed at the end of the season despite narrowly keeping the club in Ligue 1.
Still, who has never played professionally, chose to pursue a coaching career at a very young age. He began in Belgium at Lierse and Beershot before moving to France with Reims, where he initially served as assistant to Spaniard Oscar Garcia before taking over as head coach in October 2022 until 2024.
He then joined Lens on a three-year contract, but left the club at the end of the first year to be with his ill partner in England.
He had signed for Southampton at the start of last season but was dismissed as early as November 2nd, after just the 13th round of Championship fixtures.