He has since made 71 debuts for the Blues, helping them win the Champions League, Europa League and Super Cup.
Lyon are 17th in the French top flight, having picked up just one point from their opening two league games. Chelsea defender Emerson Palmieri has joined Ligue 1 side Lyon on loan until the end of the season.
The 27-year-old won Euro 2020 with Italy this summer, joined Chelsea from Roma in January 2018.