Ridsdale resigned from his post as Leeds chairman last month to be replaced by Professor John McKenzie.
A statement sent to the Stock Exchange on Thursday morning read: "The board of Leeds United announces that Peter Ridsdale has resigned today as a non-executive director.
McKenzie commented: "Peter has other business interests that he wishes to pursue and we have agreed that it is in the best interests of both parties that he stands down from the board of Leeds United and of the football club."