Guava (Psidium guajava L.) improvement is constrained by a limited understanding of genetic variability and heterosis for nutritionally important traits, particularly under semi-arid tropical conditions. This study aimed to assess genetic variability, heterosis, and trait relationships for yield and key phytochemical and mineral attributes in guava. A total of 10 parental genotypes, 20 hybrid accessions, and two standard checks were evaluated under semi-arid conditions of western India. Substantial variability was observed across morphological, biochemical, and mineral traits, with fruit weight ranging from 100.38 to 523.19 g and ascorbic acid content from 103.70 to 300.87 mg/100 g. High genotypic and phenotypic coefficients of variation, along with high heritability and genetic advance, indicated strong genetic control and predominance of additive gene effects for most traits. Notably, traits such as lycopene, magnesium, and fruit weight exhibited high variability and improvement potential. Heterosis analysis identified superior hybrid combinations, particularly VL & times; SP (H-2/20) for fruit weight and G-15 & times; VL (H-1) for ascorbic acid content, demonstrating the effectiveness of hybridization for enhancing both yield and nutritional quality. Multivariate analysis further revealed that yield and nutraceutical traits jointly contributed to major variation, indicating the possibility of simultaneous improvement. A Bayesian regression approach provided preliminary evidence of a positive but uncertain association between productive efficiency and total soluble solids, highlighting the need for larger datasets. The study demonstrates that heterosis can be effectively exploited to improve both productivity and nutraceutical quality in guava, providing a strong basis for the development of superior cultivars adapted to semi-arid environments.