Jamun (Syzygium cumini L. Skeels) is a nutritionally and medicinally important underutilized fruit tree whose commercial development has been constrained by the absence of officially released varieties and the limited systematic evaluation of germplasm from India's semi-arid production zones. Sixteen S. cumini genotypes, comprising three established named cultivars (Konkan Bahadoli, Chintamani and AJG-85), three institutional Kawadimatti Jamun Selections (KJS-01, KJS-02 and KJS-03) and ten uncharacterized farmer-maintained accessions (JG-1 through JG-10), were evaluated at three geographically distinct sites in the North-Eastern Dry Zone of Karnataka during 2025–26, following the Distinctness, Uniformity and Stability (DUS) guidelines of the PPV&FRA (2015). Tree and canopy architecture, fruit and seed biometrics, pulp recovery, yield per tree, and a comprehensive suite of biochemical quality parameters at commercial harvest were recorded. Significant variation was observed among the genotypes for all quantitative traits. Konkan Bahadoli recorded the highest fruit weight (15.62 g), pulp content (81.70%), pulp-to-seed ratio (4.53), and total soluble solids (TSS) at harvest (19.00 °Brix), establishing it as the superior genotype for fresh-market consumption. AJG-85 recorded the highest total sugar content (21.25%) and reducing sugar content (13.00%). KJS-01 recorded the highest fruit yield (258.00 kg tree-1), the greatest number of fruits per panicle (22.00), and the highest ascorbic acid content (44.26 mg 100 g-1), identifying it as a promising genotype for productivity-oriented commercial cultivation. JG-2 recorded the highest TSS-to-acid ratio at harvest (26.43) and the lowest acidity (0.74%) among the farmer-maintained accessions, indicating favourable fruit palatability. These findings provide a baseline for the multi-site morpho-pomological and biochemical characterization of S. cumini germplasm from this agro-climatic zone using DUS guidelines. The results can support variety recommendation, participatory breeding, and cultivar development in semi-arid Karnataka.