After meeting Van Persie last week, the former United No.1 says that his fellow Dutchman is delighted with how quickly he has settled into life in Manchester.
Van der Sar told the Sunday Mirror: "Robin is really happy in Manchester - in fact, he is over the moon with the choice he made to go to United.
"It is well known that Robin spoke to me before he made a decision about his future and I told him what a beautiful club Manchester United is."
Van der Sar made 186 appearances for United in a six-year stay at Old Trafford before retiring from the game last season.
He added: "The fact that it is all working out so well now, with Robin scoring so many goals in his first three months at the club, is absolutely fantastic.
"I met Robin when I travelled to Manchester to see the new statue of Sir Alex Ferguson being unveiled at Old Trafford last week.
"And I can tell you that Robin absolutely loves his new team.
"Of course, it could have worked out very differently.
"But the lads at United know that Robin adds real quality. In fact, he is in the superior category."