On 11 December 2012, he signed a contract until the end of the 2013–14 season with PAOK and made his club debut on 6 January 2013 against Panthrakikos. He would wear number 28 on his jersey. On 24 January, he scored his first goal with PAOK in the Greek Cup against Kallithea. On 3 March 2013 Katsouranis scored his first goal in the Greek Super League with PAOK in a 4-2 win against Panionios. He formed a strong partnership with Gordon Schildenfeld in the central defence reducing to a great extent the goals which PAOK conceded. On 27 August 2013 Katsouranis scored against Schalke 04 for the Champions League playoff in a 2–3 loss.