The 31-year-old made headlines across Europe during his remarkable start to life in the Reims hotseat, having gone 14 games unbeaten in all competitions in the 2022-23 season.
Still quickly became the subject of internet popularity after it was revealed that playing the Football Manager and Championship Manager games inspired his coaching career, stopping playing at the age of 17 to focus on his managerial duties.
Still started out as a video analyst before transitioning into a head coach role, but as he did not hold a UEFA Pro Licence when he took over at Reims, the Ligue 1 club were fined €25k (£21k) for every game he managed.
Reims finished 11th in the 2022-23 Ligue 1 season thanks to Still's efforts, and the 31-year-old - who was born in Belgium to English parents - was quickly linked with a move to a Premier League or Championship club.
After a five-match winless run, Still left his role as Reims manager just before the end of the 2023-24 season and was viewed as the leading contender to take the Sunderland job following Michael Beale's departure.
Still 'rejected Sunderland due to internal concerns'
Talks between Still and the Black Cats were reportedly progressing positively, albeit not to the point of an agreement, as Still has now penned a three-year contract with Lens until the summer of 2027.
"We are delighted with the arrival of Will Still at the Racing Club de Lens. Will was our top priority to take up the position of coach and start the new cycle that is opening at the club," Lens director Pierre Dreossi said. "Will is not only a promising coach who has broken records for precociousness, he is a unifying personality obsessed with winning.
"A true enthusiast, conqueror and fine tactician, Will Still left his mark on the Stade de Reims, where he obtained convincing results, notably a historic series of 19 matches without defeat. We are happy to welcome Will, his leadership and his communicative energy to La Gaillette and Bollaert-Delelis!"
Still will replace Franck Haise at Lens after the former Sang et Or boss left his post to take up the role of head coach at Nice, having overseen a meteoric rise for the Stade Bollaert-Delelis outfit.
Lens were promoted back to Ligue 1 in the curtailed 2019-20 season and quickly established themselves as a European-challenging team, finishing just one point behind champions Paris Saint-Germain in the 2022-23 season.
Les Sang et Or also beat Arsenal at home in the 2023-24 Champions League group stage and placed seventh in Ligue 1 last term, thereby earning a spot in the Europa Conference League qualifying playoff round.
A report from the Hull Daily Mail claims that Still turned down the chance to join Sunderland due to concerns over staffing and investment, while ex-Hull City boss Liam Rosenior is now the favourite to take charge of the Black Cats.