This study aligns with the 2030 United Nations Sustainable Development Goals (SDGs) 2 and 13, which focus on achieving sustainable agriculture to end hunger and taking climate action to combat climate change risk factors. It aims to investigate the direct impact of climate change on agriculture. Additionally, it examines the moderating effect of public policy effectiveness—a key determinant of growth—on this relationship in the most agriculture-dependent countries in Africa and Asia. For this purpose, we constructed a strongly balanced long-macro-panel dataset spanning 1990 to 2021 from Climate Watch, World Bank and United Nations databases. To ensure robust empirical findings, three estimators were employed in this study: the Mean Group (MG), Pool Mean Group (PMG), and Dynamic Fixed Effect (DFE). Controlling for temporal determinants of growth, estimation results for the full-sample find that the coefficient of climate change (carbon emission) exhibits a negative, elastic (2.48), and statistically significant impact on agriculture. Similarly, policy effectiveness exhibited an elastic negative impact on agriculture in the short run, which we attributed to an impact lag. The major contribution of the study is the finding of a long-run counteracting effect of policy effectiveness on climate change’s long-run adverse impact on agriculture output. In addition, sub-sample comparative analyses were also conducted in Africa and Asia. While the results align with the full sample model, minor differences were observed in the contradictory impact of human capital and policy effectiveness. The study provides various recommendations, such as investments in drought-resistant crops, alignment of agricultural policies with sectoral needs, and governance stability for dealing with political transitions.