The goalkeeper joined Ajax after moving from ADO Den Haag and had been with the Eredivisie giants and their prestigious Academy since 2017.
The Dutch teen has to make his first team debut but van den Heuvel has been capped by Netherlands at youth level for the under-15s, 16s and 17s.
The youngster has signed a deal that runs until the summer of 2023 and becomes the fourth young player to join Leeds this summer following the arrivals of Charlie Allen, Cody Drameh and Joe Gelhardt.
The new goalkeeper will initially link up with United's under-23s.
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Thank you Laura Collins