Zou, the top seed and world champion, followed up his success in Beijing four years ago with a 13-10 triumph over Pongprayoon.
A warning in the third round for the Chinese for negative tactics appeared to give Pongprayoon a chance of victory, but just moments later he was given the same penalty.
Meanwhile, Luke Campbell realised his lifetime dream as he defeated Ireland's John Joe Nevin 14-11 to claim the Bantam Weight title at the ExCeL.
Campbell landed a superb left-hand counter in the final round to floor his opponent, who had beaten him in 2009 before the Briton gained revenge with a close win in last year's World Championship semi-finals.
Campbell was in tears as the verdict was announced and he accepted the congratulations of his cornermen, saying: 'I'm very emotional right now. The plan was to stay calm and stick to the boxing and throw my punches down the middle.'