Van de Beek has opted to join Ole Gunnar Solskjaer’s side ahead of Barcelona, who were also chasing his signature.
Barcelona were delaying over a deal as they wanted to offload some of their own players to raise funds in order to match the £49million price tag placed on his head.
But they have been beaten to the chase by United and the player is set to travel to Manchester next week in order to sign up at Old Trafford, according to Sport.
Van de Beek has been promised an exit by Ajax chiefs this summer and was left out of their friendly matches against Eintract Frankfurt and Union Berlin this weekend.
Ajax boss Erik ten Hag confirmed after the game Van de Beek was not injured.
He said: ‘There are indeed developments that keep him out of the squad [to face Eintracht Frankfurt].’
It’s a blow to new Barcelona boss Ronald Koeman, who is a big admirer of Van de Beek.
He is overseeing a big clearout at the Camp Nou, while attempting to handle Lionel Messi’s push for a summer exit.