On 17 October 2008 it was announced that Eriksen had signed a two-and-a-half-year contract with Amsterdam-based Ajax. The transfer fee received by OB was estimated at €1 million (£847,199). He worked his way through the youth teams, and was promoted to the first team squad in January 2010, where he was given the number 51 shirt. Within the month, he made his first team debut for the Dutch team in the Eredivisie on 17 January 2010 against NAC Breda. Ajax manager Martin Jol compared him to the likes of Ajax youth products Wesley Sneijder and Rafael van der Vaart and described him as a good reader of the game in the traditional "number 10" role like the two Dutch internationals and Danish legend Michael Laudrup, who also played for Ajax.