The Oscar-winning actor celebrated the landmark with two nights of shows in the Big Apple, performing with his longtime partner Jan.
Celebrity guests including Nathan Lane, Tony Bennett and Donald Trump turned out to see the Let's Put On a Show gigs which took place on Sunday and Monday ahead of the star's actual birthday on Wednesday.
Rooney was pictured blowing out candles on a specially-made cake to celebrate the occasion.
TV host Regis Philbin, who was in the audience, tells NY1.com, "Celebrating his 90th birthday, after all these years. When I was a little kid, I used to watch him when he was in his heyday, and it was a great show tonight, it really was, it meant a lot to a lot of people."