It's understood Luiz was informed by new PSG coach Unai Emery that he wouldn't be a first-choice at the start of the season.
Upon learning of Luiz's sale, Blaise Matuidi tweeted: "Thank you my brother for all the good times, I'll miss you. Our paths will cross again. Stay as you are, a big man with a big heart."
Luiz was quick to reply to his former teammate with a cryptic message.
"I love my brother! You know why I'm leaving! I hope to see you soon! I already miss you."