The 25-year-old, who started his career with Ajax, has signed a one-year contract with the Dutch side.
His agent Winnie Haatrecht told Dutch paper De Telegraaf: "Ryan knows the club, the coach and hopes to have a big contribution in the further development of the team.
"Frank (De Boer) knows Ryan from his time at the Dutch national team and knows he can use him as left winger or as striker. An advantage is that Ryan was not injured last season."
Ajax boss Frank De Boer said: "There were many clubs interested in Ryan, however, Ajax was directly the number one choice."