This study explores the asymmetric effect of energy sources and economic growth on the environmental quality (carbon dioxide emission) in WAMZ with a view to testing the efficacy of EKC hypothesis. The study adopts Panel Non-Linear Autoregressive Distributed Lag (PNARDL) Model to a panel of six WAMZ countries with data covering 1990 to 2016. Results indicate that RGDP outcome for zone does not support the EKC hypothesis. Findings showed a long-run asymmetric relationship between renewable energy-carbon emission and between economic growth - CO2 in WAMZ, while there exists no long-run asymmetric association between non-renewable (fossil fuel)-Carbon dioxide emission in WAMZ. We conclude that negative shock to renewable energy use and shocks to economic growth are factors that improve environmental quality in WAMZ. Since the use of non-renewable energy shows positive but insignificant impact on CO2, we recommend the use of renewable energy for WAMZ in order to mitigate the damage done by fossil fuel.