Luiz left Chelsea last year in a record £50 million ($74.7 million, 70.8 million euros) transfer for a defender and he returned to haunt Stamford Bridge as PSG went through on away goals following a 3-3 aggregate draw.
The 27-year-old celebrated with wild abandon after his goal, an emphatic 86th-minute header, took the tie to extra time, but later apologised for any hurt he had inflicted upon the fans of his former club.
“Tonight was good for me to score,” he told Sky Sports. “I said I wouldn’t celebrate, but my emotions I couldn’t control. Thank you to Chelsea and sorry I celebrated because I was so emotional.
“It is amazing for everyone, amazing for Paris the club, for Paris the city. We did a great game. We tried to win the game.
“I am happy to be in the next round, but we have a long way to go to win the Champions League. We have to keep our feet on the floor.”
PSG had Zlatan Ibrahimovic sent off for a first-half foul on Oscar and fell behind to an 81st-minute Gary Cahill strike, but Luiz’s equaliser kept the tie alive.
Eden Hazard restored Chelsea’s lead with a penalty after Thiago Silva had been penalised for handball, but the PSG captain atoned with a late looping header that sent the French champions into the quarter-finals.