The ex-England midfielder, 37, signed a five-month deal and will donate his salary – of at least £1m – to charity.
“I’m excited, it’s something we’ve been working on and talking about for quite a while,” he said on Thursday.
“I won’t receive any salary. My salary will go to a local children’s charity. That’s one of the things we are excited and proud to do.”
He added: “It’s something the guys [PSG management] do, but obviously it’s a very good figure. That’s one thing we’re very excited about. To be able to give a huge sum to a children’s charity in Paris is very special.”
Beckham has been without a club since leaving MLS side LA Galaxy in December and has been training with Arsenal.
The former England captain had firm offers from 12 different clubs but has opted for Ligue 1’s big spenders.
Despite recently announcing he was to permanently base his family in London, Beckham always said he would make a decision on his next move based on “footballing reasons”.
PSG have spent more than £200m in the last 18 months, and are managed by Carlo Ancelotti – who was in charge of AC Milan during Beckham’s loan spell there. They are also still in this season’s Champions League and will face Spanish side Valencia in the last 16.
The Paris club are currently top of Ligue 1 and already have a squad that includes Zlatan Ibrahimovic, Thiago Silva, Lucas Moura and Ezequiel Lavezzi.
“I was lucky to work with Carlo and Leonardo [director of football] for a few months,” Beckham said. “Carlo was one of the best managers I’ve played for so it’s exciting on a number of levels.
“[Ibrahimovic] is one of the players I’m excited to play alongside. Ibra was someone I’ve watched for many years, in my early days playing for England against Sweden, and I always felt he could be one of the best players in the world.
“I watched a lot of games last year and a lot of games this season. There’s a lot of talent in this team.”
Beckham, who made a record 115 outfield appearances for England, was part of the Manchester United side that famously beat Bayern Munich to win the 1999 Champions League.
He left Old Trafford for Real Madrid in 2003, before agreeing his move to LA Galaxy in January 2007 and making his debut for the club in August in that year.
He attracted criticism from some Galaxy fans after agreeing loan moves to AC Milan in 2009 and 2010 which meant missing some of the MLS season.
And he brought an end to his five-and-a-half-year spell in the United States on 2 December after winning the MLS Cup for the second time.
At PSG, Beckham will be hoping to win a league title in a fourth country, having already enjoyed success at Manchester United and Real Madrid in Europe before moving to Major League Soccer.
Beckham had been close to joining PSG last January but opted to stay in California for one more season.
“I don’t know if this will be my last contract,” Beckham said.
“People have been speculating about that for a number of years, but I continue to play and sign contracts. I will see how I feel but I want to play as long as possible. My passion is football. It always has been. When I play football it is not about the biggest contract.”
He also revealed that his sons Brooklyn, 13, Romeo, 10, and Cruz, seven, will stay in London to go to school along with his wife Victoria, 38, and their one-year-old daughter Harper.