Climate change presents a significant threat to agricultural livelihoods in Nigeria, particularly for smallholder poultry farmers. This study examined climate vulnerability and food security among chicken-rearing households in southern Nigeria. Using a multistage sampling technique, data was collected from 987 households across four states in the region. Household food security was assessed using the Household Food Insecurity Access Scale (HFIAS), while climate vulnerability was evaluated using the Intergovernmental Panel on Climate Change’s Livelihood Vulnerability Index (LVI–IPCC), comprising exposure, sensitivity, and adaptive capacity components. Descriptive statistics revealed moderate to high vulnerability levels across the sample. Independent sample t-tests showed that rural households had a significantly higher adaptive capacity than their urban counterparts (t = 2.27), while urban households exhibited significantly greater sensitivity to climate risks (t = -2.11). Also, 91.0% of the respondents were moderately food-insecure. No significant differences were observed in the exposure levels (t = 1.68) or HFIAS scores (t = 0.08) between rural and urban households. The results from the Tobit model indicated that adaptive capacity significantly reduced food insecurity (z = -6.26), while a higher constraint burden increased it (z = 4.98). Female-headed households (z = 2.58) and those that reared more Fulani ecotype birds (z = 2.16) were more food-insecure, while literacy in English significantly improved food security (z = -3.64). Climate exposure and sensitivity were not statistically significant in explaining HFIAS scores. These results highlight the need for context-specific adaptation strategies that enhance rural households’ resilience, address production constraints, and promote inclusive access to information and literacy.