The South Korean will return to his home country after an unsuccessful first season in the Eredivisie which saw him make just 12 appearances for the Rotterdam side.
"We hope that this move will allow Lee to start playing regular football," said technical director Peter Bosz on Feyenoord's official website. "We have a plan for how we want Feyenoord to play next season and there is no place for Lee in that."
However, Bosz believes that Lee could still make a return to the side if he impresses in the K-League next term.
He added: "We hope that Lee will play well. We will try to follow him closely this year."