The Ivorian striker joined for 22.5 million euros, and will wear jersey No. 22.
Haller became the most expensive player in the history of the Dutch league, surpassing his teammate’s Brazilian David Neres, who moved the 2016-17 season for 22 million euros, according to “Transfer Market”.
Haller, 26, began his career with Dutch Utrecht for two and a half seasons, having trained at the time under the leadership of Erik Ten Hag, the current coach of Ajax.
The striker scored 40 goals and made 15 in 81 games as the best performance of his career under the Dutch coach.
Then he joined the ranks of French Auxerre in the middle of the 2014-15 season, and from there to Eintracht Frankfurt, then to West Ham in the summer of 2019.
With West Ham, Haller scored 7 goals this season and scored in the English Premier League and League Cup during the first half of the current season.
Ajax are top of the Dutch league, one point behind Eindhoven after 14 rounds.
The Dutch team will meet Lille in the 32nd round of the European League next February.