The 37-year-old was unveiled as a PSG player on Thursday on a five-month contract, having turned down numerous lucrative offers after playing his last game for the Los Angeles Galaxy at the start of December.
And Ancelotti told beIN Sport: "I know David Beckham very well. Everyone talks about his image, but I want to emphasise his professionalism and quality on the pitch.
"It is true that he is not young, but he has experience. (Paolo) Maldini won the Champions League at the age of 39, so Beckham still has lots of time ahead of him."
He added: "He must train as he has returned from vacation, but he can play every position in midfield - defensive, with his passing ability, or on the right even if he does not have the speed of Lucas.
"He can help the team have a great season.
"I am very happy with his arrival. I had the opportunity to coach him for six months at Milan. It was an exceptional experience."