The global pursuit of net-zero emissions by 2050 has accelerated the transition to green economies, with renewable energy as a cornerstone for sustainable development. This study evaluates the effectiveness of green finance policies in promoting renewable energy adoption in Vietnam, comparing outcomes with South Korea and Thailand. Using a quantitative approach, we analyze panel data from 2015 to 2023 for 1,500 firms across the three countries, employing fixed-effects regression models to assess the impact of green finance on renewable energy investment and economic growth. Results indicate that Vietnam’s green finance policies significantly boost renewable energy adoption but lag behind South Korea and Thailand in private sector engagement and policy flexibility. Infrastructure constraints and high financing costs remain challenges. Policy recommendations include adopting auction mechanisms, enhancing grid infrastructure, and fostering regional cooperation to support Vietnam’s Socio-Economic Development Strategy 2021–2030, contributing to sustainable growth and global climate goals.