Kleff joined Borussia Mönchengladbach in 1968 and played for the team from 1968 to 1979. He also played for Hertha BSC, Fortuna Düsseldorf,Rot-Weiß Oberhausen, VfL Bochum and for the promoted FC Salmrohr in the Second Bundesliga. At this time he was 40 years old. At the end of his long career Wolfgang Kleff had played 433 matches in the Bundesliga and 56 games in the 2nd Bundesliga.