Ajax have confirmed on their official website that they have reached an agreement with Lasse Schone over a contract that will run until the summer of 2015.
The 25-year-old had an expiring deal at NEC and leaves the Nijmegen side on a free transfer.
The midfielder is a product of the Lyngby youth academy, but left the Danish side for Heerenveen at the age of 16.
Schone failed to break into the first team at the Friezen, though, and eventually joined NEC in 2008 after a two-year spell at De Graafschap.
The Denmark international has made 107 Eredivisie appearances for NEC, scoring 23 goals in the process.
Schone joins compatriots Christian Eriksen, Nicolai Boilesen and Viktor Fischer at Ajax.