Kim, 28, spent the last two seasons with 2012 AFC Champions League winners Ulsan Hyundai, and scored in their 3-0 win over Saudi Arabia's Al-Ahli in that year's final. He boasts considerable experience in Korea Republic's top flight, having also played for FC Seoul as well as doing a stint with Gamba Osaka in Japan's J-League in 2011.
Mariners coach Phil Moss said the former South Korean youth international would prove a big asset to the club. "We've taken as much time as we've needed to land our man, and based on all our due diligence we believe Kim Seungyong will have a major impact for our club on and off the field," Moss said.
"It made a lot of sense to me to investigate bringing a top quality Asian player to the Mariners, especially considering our involvement with the 2014 AFC Champions League. We see it as a massive opportunity to tap into the Korean community in Australia, and a chance to generate further awareness of our Club in Asia," he said.