The former England captain, who joined PSG on a five-month deal last month, came off the bench in the 76th minute to become the 400th player to represent the club.
PSG were leading 1-0 at the time thanks to Lucas Moura's deflected early opener at the Parc des Princes, and Beckham helped his new side seal victory with a second goal through Zlatan Ibrahimovic in injury-time
Beckham chipped a pass into the left-hand channel of the area for Jeremy Menez, whose cross was tucked in by Ibrahimovic for his 22nd goal of the season.
The win restored PSG's three-point lead at the top of the Ligue 1 standings over Lyon, who beat Lorient earlier in the day, while third-placed Marseille are now eight points adrift of the leaders, who are chasing their first title in almost two decades.
A delighted Beckham said on his club's website, www.psg.fr: "I'm very happy tonight [Sunday], mainly because of the victory.
"We have played better but it was very important to win. Today [Sunday] was the perfect day. Not only because I'm the 400th player in the history of the club but also because I'm part of a very special team.
"The welcome from the supporters was unbelievable, and I want to say thank you to them."
PSG boss Carlo Ancelotti had waited to give Beckham his debut as the former Manchester United and Real Madrid built up his fitness having not played a competitive match since he helped the Los Angeles Galaxy to the MLS Cup title - his final game for the club after a five-year stay - last December.
Beckham could now make two appearances in four days for his new club after former Chelsea boss Ancelotti suggested the 37-year-old could face Marseille again in midweek.
The Italian said: "Beckham played because he was in the right physical condition and certain players needed a breather. It could be that David Beckham will play on Wednesday in the Coupe de France."