An agreement is in place for the 23-year-old to move to Old Trafford for around £40 million.
United are set to discuss personal terms with Van de Beek before the Netherlands international undergoes a medical ahead of the transfer.
United manager Ole Gunnar Solskjaer has tracked Van de Beek for more than a year with the club making an enquiry about his availability in January before signing Bruno Fernandes.
Sources have told ESPN that Solskjaer and the club see a deal for Van de Beek as a good opportunity to strengthen the squad in a window during which they have struggled to agree a fee with Borussia Dortmund for Jadon Sancho. At around £40m, van de Beek is seen as reasonably priced while at 23, he also fits into the right age bracket for Solskjaer's rebuild.
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Check out Donny van de Beek's best goals at Ajax this season as rumors of a transfer heat up.
The 23-year-old has featured for Ajax in preseason but was left out of their squad for a friendly with Eintracht Frankfurt on Saturday.
Ajax coach Erik ten Hag admitted that the move was linked to developments over the player's future.
ESPN first reported United's interest in Van de Beek -- who has two years left on his Ajax contract -- in January.
He had been linked with a move to Barcelona in recent weeks to link up with his former national team coach Ronald Koeman.
In June, Ajax director -- and former Manchester United goalkeeper -- Edwin van der Sar admitted that Van de Beek was a target for the Premier League club.
After coming through the academy at Ajax, Van de Beek made 175 appearances for the Dutch giants and played a key role in their run to the Champions League semifinals in 2019. He has been capped 10 times by the Netherlands after making his debut in 2017.
ESPN's Rodrigo Faez and Alex Kirkland contributed to this report.