PurposeThe need to improve energy efficiency as an essential factor for achieving the Sustainable Development Goals (SDGs) through green financing is one of the most important issues worldwide. It is even more important for ASEAN (Association of Southeast Asian Nations) countries because of their potential for economic growth and the challenge of their environmental problems. This paper therefore addresses the question of whether and how green finance (with the proxy of issued green bonds [GBs]) promotes energy efficiency (with the proxy of energy intensity) in the ASEAN member countries.Design/methodology/approachThe paper runs a two-stage generalized method of moments (GMM) system model for the quarterly data over the period 2017–2020. It also uses a linear interaction model to explore how the pandemic may affect the relationship between green finance and energy efficiency in this region.FindingsThe main results only demonstrate the short-term negative impact of GBs on energy intensity. Furthermore, per capita income, economic integration and renewable energy supply can be used as potential variables to reduce energy intensity, while modernization in ASEAN increases energy intensity. Establishment of digital green finance, long-term planning of a green finance market, trade liberalization and policies to mitigate the negative impacts of COVID-19 are recommended as golden policy implications.Research limitations/implicationsThe present study has several limitations. First, it accounts for explanatory variables by following a number of previous studies. This may lead to omissions or errors. Second, the empirical estimates were conducted for 160 observations due to the repositioning of GBs in ASEAN, which is not bad but not good for an empirical study.Originality/valueTo the best of authors' knowledge, there has not been any in-depth study focusing on the relationship between energy efficiency and green financing for the case of ASEAN economies.