Globally, an estimated 800 million people are currently experiencing hunger. Food insecurity remains a major concern, especially in developing countries. In sub-Saharan Africa, smallholder farmers, who are both food producers and consumers, manage 80% of all farms but face many challenges including; shrinking farm sizes, limited financial resources and dynamic farming environments. Food insecurity persists among smallholders as various uncertainties together with climate change impacts exacerbate existing vulnerabilities. However, smallholders have the potential to contribute significantly to food security at community through national scales. This research aims to provide a better understanding of food security determinants among smallholders with a focus on how they use various institutional arrangements to augment their livelihoods. Through focus group discussions and on-farm interviews, the research engaged with smallholders and non-farmers from Embu, Mt. Kenya region in central Kenya. Using a constructivist approach and guided by insights from political ecology, the research assessed smallholders’ narratives on perceptions of and experiences with food security, institutional arrangements, climate variability, and climate change. The findings offer strong evidence that smallholders’ livelihoods are inextricably reliant on their food production. Fulfilling other livelihood needs, e.g. school fees, often receives priority over satisfying a household’s dietary requirements. Cropping seasons rather than longer timescales dictate smallholders’ decision-making and planning. Resultantly, everyday uncertainties and challenges tend to subsume climate change threats while climate variability poses more impacts on their seasonal productivity. The conventional definition of food security posed by the Food and Agricultural Organization aligns only partially with the realities of farmers in the Embu region. Smallholders place greater emphasis on two food security dimensions, availability and access, paying considerably less attention to utilization and stability. While engaging formal institutions, smallholders have greater agency as members of informal groups than as individuals. This research proposes leveraging current formal and informal institutional arrangements to bolster smallholders’ food security outcomes as well as improve their adaptive capacity to climate variability and change. It recommends supporting smallholders through providing timely agro-climatic information, offering functional financing, brokering new knowledge, assisting in scenario planning for risk management, and reducing access barriers in pre-production processes.