Environmental challenges have become the focus of the pursuit of the sustainability and net-zero emissions objectives by countries. So, there is a need to comprehend what determines Environmental Policy Stringency (EPS). The paper looks at the impact of energy vulnerability (EV), energy transition (ET), urbanisation (U), Research and Development (R&D), population growth (PG) and Economic Growth (EG) on Environmental Policy Stringency. It is based on panel information of 40 countries that are committed to the net-zero emissions by 1990–2023. Advanced econometric tools, including the cross-sectional dependence test, panel unit root and cointegration tests, and estimators, such as CS-ARDL, CCEMG, AMG, Driscoll-Kraay, FMOLS, and DOLS, are used to investigate long-term relationships. Its results indicate that the variables are cross-sectionally dependent and have a long-run equilibrium relationship which implies the interdependence between environmental policies, energy systems and economic conditions across nations. According to the long-run estimates, the energy vulnerability, energy transition, R&D, and economic growth are significant factors that determine Environmental Policy Stringency. The interest of governments in stricter environmental policies and environmental governance is increasing with high-energy vulnerability and the transition to renewable energy. Economic growth is also a favourable variable in Environmental Policy Stringency that favours the EKC hypothesis. The negative effects of urbanisation and population growth, on the contrary, are negative yet statistically insignificant, which suggests that demographic variables play a weak role. Overall, the findings evidence the necessity of creating renewable energy and technology, ensuring sustainable economic growth, improving environmental policy and long-term net-zero objectives.