The Brazillian has joined the Ligue 1 champions after they agreed a reported fee of £50 million with the Stamford Bridge side, smashing the world-record sum for a defender.
The centre-back confirmed his departure from Chelsea towards the end of May when he took to Twitter and Facebook to thank fans and colleagues for their support during his three-and-a-half-year stint in London.
Luiz fell out of favour under Mourinho, along with several other first-team players, at the beginning of last season, and Goal learned of a possible move to PSG in May.
The move will now see Luiz link up with his central defensive partner for the national team, Thiago Silva, straight after their World Cup campaign, and he has already spoken of his excitement of his move to France.
The former Benfica man made 143 appearances for the Blues and scored from the spot during their Champions League final shootout triumph over Bayern Munich in 2012.
The 27-year-old revealed his departure on Facebook in May saying: "Thanks Chelsea for the three and half years of great partnership.
"I've made good friends, won many titles and those memories will last with me for ever. I'd like to thank my team-mates, all staff and all supporters (my geezers).
"I'm leaving with great sadness but at the same time excited for the new challenge that lies ahead in this great club in a city that has always enchanted me."