Evaluation of chemical characteristics of fruit crops has been successfully used for the selection of cultivars for breeding programs. In a bid to access useful information for the utilization of mango genetic resources in Nigeria, 10 mangoes (Mangifera indica L.) cultivars were evaluated for physicochemical, nutritional, antioxidant, and phytochemical characteristics at the National Horticultural Research Institute, Ibadan, Nigeria. Cultivars showed significant (P <= 0.05) variation for quantitative and chemical traits. Madoe, Saigon, Ogbomoso, and Haden had the highest values for TSS (19.25% brix), vitamin C (11.68%), pH (5.91), and shelf life (12.00), respectively. Alphonso had the highest values for starch - 1.73; reducing sugar - 0.61; amylose - 11.78 g/100 g, and some minerals (K - 20.15; Mn - 7.79; Ca - 51.50; Fe - 4.99; Zn - 32.95; Cu - 11.10, and Cr - 0.47 mg/100 g) composition, but low values for phytochemicals (phytate - 0.86 and tannin - 0.54 mg/100 g). The highest antioxidant values were recorded for Julie (DPPH inhibition 85.24%; reducing power - 2.46) and Saigon (total antioxidant 322.14 mg/100 g vitamin C equivalent). However, the least genetic similarity (2.41) was recorded between Palmer and Kent, while the highest genetic similarity (6.68) was between Ogbomoso and Edward. The total variation explained by the first four principal component (PC) axes was 71%. Results obtained from this study indicate that the mango cultivars are divergent and can be useful genetic resources for mango improvement through breeding.