‘Keitt’ mango is one of the most important cultivars, and it is usually stored at a low temperature during its commercialization to extend shelf life and reach distant markets. However, it is susceptible to chilling injury (CI) and some prestorage treatments are required to reduce the incidence of this disorder. This research shows for the first time the protective effect of a combination hot water-calcium lactate (Ca) against CI in mango fruit cv. Keitt. Fruit were subjected to hot water treatment (HWT) (46.1 °C, 75–90 minutes) or treated with 0.5% Ca or with the combination HWT + Ca, stored at 5 °C for 20 days, and ripened at 21 °C for 7 days. CI index (CII), electrolyte leakage (EL), malondialdehyde (MDA) production, bioactive compounds, antioxidant capacity [2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazil (DPPH)], and activity of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)] were analyzed in mango samples after 0, 10, and 20 days of cold storage and after ripening. Hot water treatments (HWT and HWT + Ca) were more effective than Ca in providing protection against CI as evidenced by lower incidence of symptoms and lower EL and MDA. HWT + Ca increased the content of phenolics, flavonoids, and carotenoids during the cold storage, which correlated with the antioxidant capacity by ABTS. SOD and APX showed higher activity in HWT + Ca–treated fruit, whereas CAT activity was higher in fruit with HWT and Ca. These results suggest that HWT + Ca provided CI tolerance of ‘Keitt’ mango by activation of the enzymatic and nonenzymatic antioxidant systems.