Recent developments in regional studies argue that geopolitical influence is one factor affecting the regional order. However, studies on geopolitical influence have yet to cover East Asia to explain East Asia's regional order. The quantitative approach to geopolitical influence studies still faces a methodological challenge because it uses an arbitrary weighting of geopolitical influence in developing an index. In order to address those challenges, this research deploys factor analysis as a non-arbitrary weighting system to measure the geopolitical influence of China, Japan, Russia, and the US in East Asia during the period from 2005 to 2018. Additionally, this research explores how the geopolitical influence of those countries affects East Asia's regional cooperation and integration. The research shows that: (1) China has been able to compete with the US for geopolitical influence in East Asia since 2014, and (2) Chinese, Japanese, Russian, and US geopolitical influence positively contributes to regional cooperation and integration in East Asia, with the US and China as the main contributors. The research highlights three possible causes to explain the results: China's regional infrastructure initiatives, rejuvenation of China's view on globalization, and the relative decline of US relations with the allies in the region.