The Dutch champions have paid Tottenham Hotspurs £26m for Bergwijn's signature.
The 24-year-old was keen to leave North London after falling down the pecking order under Antonio Conte.
Bergwijn joined Spurs from PSV Eindhoven in January 2020 and made an immediate impact at his new club, scoring on his debut in a 2-0 win over Manchester City.
The Netherlands international however could not cement his position in the Spurs side and made 83 appearances across all competitions, scoring eight goals and registering 10 assists.
Bergwijn made just four Premier League starts out of his 25 appearances last season, scoring three goals, including a late brace in a 3-2 win at Leicester City in January.
He has mostly played second fiddle to the likes of Harry Kane, Son Heung-Min, Lucas Moura and recently Dejan Kulusevski in the Lillywhites' attack but the recent signing of Richarlison from Everton would have further limited his chances.
Bergwijn has always impressed when called up by his national team and with the World Cup coming, did not want to lose his spot.
After rejecting offers from Ajax in January and earlier in this transfer window, Spurs have finally reached an agreement to move Bergwijn on.
"It is indicative of Steven's ambition that he chose to make the step to Ajax," said head coach Alfred Schreuder.
"He is a player with many qualities. He has enormous drive and is also very goal-oriented.
"Of course, I am happy that we were able to sign him, he adds new quality to our team."
