The former England captain has been a free agent since leaving LA Galaxy at the end of last year and has been linked with a number of Europe's top clubs.
However, he eventually opted to move to the French capital and Ancelotti has now tipped him to make a difference to his team's Le Championnat challenge.
"Beckham is a player with a lot of experience, one who can help everyone," he said. "He can help the team improve, get more experience and show a better quality of play.
"Everybody at PSG is happy for his arrival, because he is a player with a lot of qualities."