In this study, we employ the novel method of quantile mediation analysis to explore dynamic relationships among hydropower energy consumption, economic growth, and carbon dioxide emissions in Taiwan during the period between 1990 and 2020. The empirical results show that hydropower energy consumption only has a direct effect on reducing carbon dioxide emissions at a 0.2 distribution of carbon dioxide emissions. Moreover, results indicate that economic growth does not have a mediating effect between hydropower energy consumption and carbon dioxide emissions at any distribution of carbon dioxide emissions. Lastly, evidence produced by this study supports the existence of an environmental Kuznets curve in the context of Taiwan.