This study employs Structural Equation Modelling (SEM) to conduct a comparative analysis of agricultural extension systems and community-based climate adaptation strategies in Kenya and Zimbabwe, focusing on sweet potato farming. Both countries face escalating climate threats, prolonged droughts, erratic rainfall, and land degradation, but differ in institutional design and policy responses. Zimbabwe relies on a centralized extension service, while Kenya’s decentralized framework empowers local leaders and community networks. Guided by the Sustainable Livelihoods Framework, Institutional Theory, and Resilience Theory, the research integrates expert insights to explore how extension policies, land tenure systems, and local governance structures influence the adaptive capacity of smallholder farmers. The findings underscore that successful climate adaptation hinges not only on technological innovation but also on institutional coordination, contextual knowledge, and grassroots inclusion. The study concludes with targeted policy recommendations to strengthen resilience and sustainability in agricultural extension systems across sub-Saharan Africa.