Estimates of genetic parameters and knowledge of the relationship between seed yield and related traits are central to successful cowpea (Vigna unguiculuta (L.) Walp) breeding. The continuous development and advancement of cowpea populations require information on the variability and character associations among cowpea germplasms. Thus, cowpea genotypes were evaluated at Abeokuta, Nigeria during the early seasons of 2012 and 2013 to determine the genetic variability and inter-trait relationships within the germplasms. Genotype effect was significant for days to 50% flowering, seed yield and related traits. Phenotypic variances and coefficients of variation were larger than their corresponding genotypic components for all traits, except number of seeds per pod. Heritability estimates were low for seed yield and days to 50% flowering but moderate for days to maturity, number of pods per plant and pod yield; and high for 100 seed weight, number of seeds per pod, fresh and dry fodder weights. Genetic advance was high for seed and pod yield as well as dry and fresh fodder weight but was low for days to 50% flowering, days to maturity, number of seeds per pod, number of pods per plant and 100-seed weight. Based on stepwise regression and path analysis, pod yield was identified as the most important trait for seed yield and could be targeted in breeding programmes to enhance seed yield in cowpea.