Katsouranis debuted in the 1997 season for the Patra-based club Panachaiki FC. He spent six seasons at the club and by the third was already a starter. In the 2003 season he earned a transfer to AEK FC.
On June 23, 2006, Katsouranis signed for Portuguese club Benfica. He was sold to Panathinaikos in June 2009. In the summer of 2012 he was transferred to PAOK. In 2014 he had a short spell in India playing for Pune City. The 2014/2015-season Katsouranis played for Atromitos Athens before heading to Australia where he played just one game for Heidelberg United as he signed a one-match contract, with the option to extend it should they win their following FFA Cup match. Heidelberg lost and Katsouranis announced his immediate retirement.
On October 16, 2012, he earned his 100th cap as Greece down Slovakia 1-0 in Bratislava. Katsouranis assisted on the goal by crossing the ball to goal scorer Dimitris Salpingidis. At the end Katsouranis was capped 116 times, scoring 10 goals.