<p>Bottle gourd (<i>Lagenaria siceraria</i> (Molina) Standl.) is an underutilised cucurbit with important nutritional, medicinal, and cultural value in sub-Saharan Africa, yet information on its phenotypic diversity in Nigeria remains limited. This study is the first to phenotypically characterize Nigerian bottle gourd germplasm in detail. In this work, we combine genetic quantitative parameters (heritability and genetic advance) with multivariate analyses aiming at identification of superior accessions for breeding programs. Coefficients of variation for quantitative traits ranged from 8.21% for leaf length up to as much as 117.87% for fruit weight. Among the traits measured, fruit weight, number of seeds per pod, and number of fruits per plant were the highest in genetic coefficients of variation (166.9%, 95.6%, and 92.1%, respectively), while fruit, seed, and yield-related traits recorded broad-sense heritability values ranging between 0.97 and 0.99. Principal component analysis revealed that the top three principal components accounted for 52.1% of the total variation, corresponding to floral, seed fruit, and vegetative architecture traits. Hierarchical cluster analysis divided the accessions into three major clusters, with inter-cluster distances ranging from 55.6 to 332.4. Multiple Correspondence Analysis of qualitative traits differentiated the accessions into five groups based on fruit shape, fruit colour, and leaf morphology. The findings reveal a wide range of phenotypic variation among the accessions, which allows for selection, breeding, hybrid development, and conservation of bottle gourd germplasm.</p>