The Brazil defender made the switch from Chelsea to the Ligue 1 giants in 2014 and went on two win two league, two Coupe de France and two Coupe de la Ligue titles during his time there.
Luiz enjoyed his time at the Parc des Princes but felt the chance to win a Premier League title was too good to turn down with a return to Stamford Bridge.
He told the official Chelsea magazine: "I was also very happy in Paris. I was winning trophies, I was having a great life there but I know me and I like to have new challenges in my life, to have ambition.
"One of the reasons I decided to come back here is because I know the Premier League well but I never had the opportunity to win it, so it is still one of my goals in my career."