Moisander has signed a three-year contract and joins the Eredivisie champions for a fee believed to be around €3million.
“I want to continue my development and Ajax needed a new centre-back following Vertonghen’s exit. I realise that it won’t be easy to follow in Jan’s footsteps,” Moisander told to De Telegraaf.
“Frank de Boer believes that I can become an important player, though, with my specific qualities and my experience.”