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A field experiment was conducted at the Teaching and Research Farm, Emaudo Annexe, Ambrose Alli University, Ekpoma, to assess genetic variation among four watermelon varieties: Kayack, F1 Heracles, Greybelle, and Sweet Diamond. The study employed a Randomised Complete Block Design (RCBD) with four replications. Data were analysed using Analysis of Variance (ANOVA) and genetic parameters including heritability (H²), genetic advance (GA), and genetic gain (GG). Kayack consistently exhibited superior vegetative and yield traits at 3, 6, and 9 weeks after planting (WAP). It recorded the tallest plants (12.14 cm, 37.71 cm, 119.62 cm), highest number of leaves (7.28, 29.75, 76.75), largest leaf area (104.00 cm², 1373.68 cm², 2793.35 cm²), thickest stems (1.19 cm, 1.76 cm, 1.83 cm), and highest branch numbers (4.25, 6.50). It also showed the earliest flowering (38.50 days) and maturity (64 days), and the best fruit traits: length (19.98 cm), diameter (14.5 cm), circumference (332.5 cm), and fresh weight (35.62 t/ha). Traits such as leaf area, stem girth, number of branches, flowering, maturity, and fruit length showed high heritability and genetic advance, indicating the predominance of additive gene action and potential for improvement through selection. Conversely, traits with low heritability and genetic advance were considered less dependable for selection. Kayack’s early maturity and high yield demonstrate its suitability for cultivation. It is recommended for adoption by farmers, while extension agents should promote improved varieties and provide training on climate-resilient practices to boos