Against the background of intensifying global environmental risks and the elevation of ecological civilization construction to a national strategy, the Chinese government has continuously increased its investment in environmental governance, improved relevant laws and regulations, and strengthened environmental supervision and accountability mechanisms, leading to significant improvements in objective environmental quality. To examine the changes in public subjective evaluations of governmental environmental governance under the improvement of objective environmental quality, as well as the differences between evaluations of the central and local governments and their evolving trends, this study uses four waves of data from the Chinese General Social Survey (CGSS) in 2003, 2010, 2013, and 2021 and applies an age-period-cohort model to investigate the changes in evaluations of governmental environmental governance and central-local differences. Results indicate that the evaluation of the central government’s environmental governance is substantially higher than that of local governments, with a strong positive correlation between the two. Age effect test reveals a “U”-shaped trend for the evaluation of local governments’ environmental governance. In contrast, the period effect test shows that the evaluation of the central government’s environmental governance peaked in 2021 compared to other periods, and that of local government followed a pattern of initial decline followed by recovery. Cohort effects are insignificant for both levels. It is inferred that the evolution of public evaluation of government environmental governance and central-local disparities may stem from the interplay of multiple factors, including differentiated action logics between central and local governments, individual social pressures, early environmental education, and objective environmental quality. This provides insights into the mechanisms underlying public evaluation dynamics in China’s environmental governance context and offers policy implications for improving China’s environmental governance system, optimizing the division of responsibilities between central and local governments, bolstering youth environmental education, and enhancing public satisfaction through sustained enhancements in environmental quality.