Ajax have paid an initial fee of 15.7 million euros for Promes, who has signed a five-year contract, the club announced.
It is a return to the club for the 27-year-old forward, who was originally in their youth setup but was released and instead made his breakthrough at FC Twente and then Go Ahead Eagles, when Ajax coach Erik ten Hag was in charge there.
Promes, who has won 38 caps for the Netherlands, moved to Spartak Moscow in 2014 and Spain last year, where he had a contract until 2023.
Ajax won the Dutch league and cup double this year and reached the Champions League semifinal, ensuring an estimated 90 million euro windfall for the club.
Dutch reports said their next target was 21-year-old Steven Bergwijn from rivals PSV Eindhoven.
De Jong was sold to Barcelona for 75 million euros and according to local media Matthijs de Ligt and Donny van de Beek are expected to follow in the coming weeks in more lucrative sales for Ajax.
(Reporting by Mark Gleeson; Editing by Sudipto Ganguly)
