The French giants had already announced that the Brazilian would be playing at the Parc des Princes next season, with the media reporting that the move would be for around £40 million.
The big surprise today though was that the move actually went through for £50 million, a quite unbelievable figure for a 27-year-old central defender.
It means PSG have now spent over €130 million on three Brazilian centre backs after the past transfers of Thiago Silva and Marquinhos.
And for Chelsea it represents a phenomenal piece of business, especially considering Jose Mourinho rarely favoured the player in his preferred defensive position.
The Blues have already brought in Kurt Zouma to the squad as a younger defensive option, and now have a huge war chest with which to dip into the transfer market if they wish to.
Mourinho has also signed Cesc Fabregas and Diego Costa, for little more than they sold Luiz for, and it may even be the case that the Portuguese merely utilises Branislav Ivanovic centrally if need be, allowing for Cesar Azpilicueta to move to right back and the inevitable left back purchase to come in.
There are few that would rate David Luiz within the world's top five defenders, yet the fee he has gone for makes him the most expensive in that position of all time, and moves him into the overall top 10, level with former teammate Fernando Torres.
The transfer fee matters little to the defender, with Luiz just looking forward to a new chapter in his career.
"Right from the very first contact I had with Paris St Germain I was very happy," he said.
"It's a big club with a great history, a new step in my life, and I'm impatient to play and show what I can do.
"I will be defending the colours of one of the biggest clubs in the world. It will be a great time for me, both professionally and personally. I want to enjoy myself and, if possible, win as much as possible."