On 18 December 2011, Van Rhijn made his first team debut in the Eredivisie, against ADO Den Haag. The match ended in a 4–0 win for Ajax at the Amsterdam Arena, which saw Van Rhijn playing the full 90 minutes in place of Alderweireld, who was sidelined due to an injury. Moving from the centre back role to the right back position, Ajax has used Van Rhijn extensively as a replacement for an injured Gregory van der Wiel. The 2012–13 season saw Van Rhijn becoming the first-choice right back under manager Frank de Boer following the departure of Van der Wiel. Van Rhijn scored his first official goal for Ajax in a UEFA Europa League home match against Steaua București in the round of 32 on 14 February 2013. The match ended in a 2–0 home win for Ajax, with Van Rhijn scoring in the 48th minute.
