Van der Kuijlen started out with a semi-professional contract; signing a contract with PSV Eindhoven meant that he could also work at Philips. On weekdays, he would work as a warehouse worker. Van der Kuijlen debuted in a friendly match on 7 August 1964 against SVV, scoring five goals in a 6-1 victory. His Eredivisie debut was on 23 August 1964 in a match against Fortuna ’54. Van der Kuijlen scored the only goal in a 1-2 loss. In the second league match, he managed to score three goals in PSV's 3-1 victory over SC Enschede. In his first season at PSV (as the youngest player in the league), the team finished second in the league and Van der Kuijlen also finished second in the Eredivisie top scorer ranking with twenty goals. In the 1965-66 season, Van der Kuijlen, who just turned 20, became league topscorer with 23 goals. In the final league round, PSV managed to beat FC Twente 1-7 in Enschede; Van der Kuijlen scored four times in that match.