PSG are believed to have paid as much as £50m for the Brazilian, who claims that his own desire to begin a new stage of his career was the real reason for his exit.
"It was my choice, my cycle had finished." Luiz told Reuters. "I decided to move and PSG showed me a nice plan for the moment and for the future. When they showed it to me I decided it was where I wanted to go.
"Chelsea offered me a new contract. It was my decision to leave. I don't have a problem with Mourinho.
"I was happy at Chelsea as well. I respect the club and the fans."
Luiz made 143 appearances in all competitions for Chelsea after joining the club from Benfica in 2010.