The Portuguese is set to be unveiled as United's new manager this week which will see him replace Louis van Gaal, who was sacked on Monday.
Mourinho's much talked about move to Old Trafford now looks almost certain to take place and fellow manager Ancelotti, who will take the reins at Bayern Munich this summer, believes it is an astute move by the Red Devils.
"I think it is a good wedding because Mourinho really knows the Premier League well," said Ancelotti.
"He is one of the best coaches in the world and Manchester United at this moment need someone who can improve what they did in the last two years with Louis van Gaal."
Ancelotti added: "The last year they (United) showed they have really good young players. And maybe with Mourinho they could have a step forward."