Crystal Palace have confirmed the signing of defender
De Boer handed his compatriot his professional debut while coach of Ajax, and clearly rates the youngster highly.
The deal was expected to be completed prior to Palace's involvement in the pre-season Asia Trophy, but was reportedly held up
Riedewald has proved his versatility for Ajax, playing at centre-back, left-back and as a holding midfielder.
Speaking following his arrival, Riedewald told Palace's official website:
“The Premier League is a great competition to be involved in and it is a great opportunity to be working under Frank de Boer once again having been with him at Ajax.
“I look forward to meeting my new team mates and then getting the chance to be out on the training ground and getting ready for the new season.”
Manager De Boer added:
Riedewald made 16 league appearances last season, as well as six starts in Ajax's Europa League campaign which ended with defeat against Manchester United in the final.