Beckham, 37, signed a five-month contract with the cash-rich Ligue 1 club after leaving Los Angeles Galaxy at the conclusion of the MLS season in early December.
"I won't receive any salary. We have decided my salary will go towards a local children's charity in Paris and that is one of the things we are very excited and proud to do," he said at a packed press conference.
"I am very lucky to have earned what I have earned throughout my career."
He and Spice Girl wife Victoria are said to have donated over £1 million to children's charities already.
They have four children themselves, Brooklyn Joseph, Romeo James, Cruz David, and Harper Seven. Beckham said that his family will live in London as they now attend school there.
Asked how his French was, the former England captain said he would have to "brush up".
"I haven't spoken French for quite a few years, since I was a school - so that is definitely a few years," he said.
He was then asked to say something in the language and replied: "Bonjour."
On the deal, he said: "We've been talking about it for quite a while. I'm delighted it's happened.
"I'm lucky - I got more offers at 37 than I'd had in my career. I chose Paris because I can see what the club are trying to do. It's an exciting city, but now there is a club that is going to have a lot of success in the next 10, 15, 20 years.
"I'm very honoured that I'm part of this - honoured to be part of the future of PSG."
'Le Spice Boy' has been training with Arsenal in recent days, leading to speculation that he would sign for the Gunners. However he insisted that a move back to the Premier League was never on the cards.
"I had offers from Premiership teams. I've always said that I would never want to play for another English club because I have a lot of history with Manchester United," he said.
He has only faced United while on loan from Galaxy - whom he signed for in 2007 - at AC Milan.
PSG face Valencia in the last 16 of the Champions League and currently sit top of their domestic table on goal difference. Beckham will link up again with coach Carlo Ancelotti and sporting director Leonardo, having worked with both men during his two loan spells at Milan.
PSG have financial clout - they are Qatari-owned and have been the highest-spending club in Europe in the past year, convincing Beckham to turn down 12 formal offers from around the globe including South America, North America, South Africa, Russia, China and the Middle East as well as Europe.