The chapter attempts to examine East Asian regionalism from the perspective of power. Extremely asymmetric power distribution had driven regional weak powers to form ASEAN and put them in the driver’s seat of regional integration. However, they failed to guide regional great powers Japan and China into cooperation due to power deficiency. The ensuing great power rivalry between China and Japan has derailed the East Asian regionalism on the move. This chapter also evaluate how the emerging China’s regional hegemony will affect the future of East Asian regionalism. This chapter concludes that asymmetric power distribution and relative power concerns have worked as both prompting and failing factors in East Asian regionalism.