<p><i>Tamarindus indica</i> is a plant species widely used in the food industry, and phytochemical studies have revealed its potential as a source of antioxidant compounds present in its pulp, seeds, and leaves. This study aimed to establish in vitro cultures of <i>T. indica</i> for the production of phenols with antioxidant capacity. Seedlings from 30-day-old in vitro-germinated seeds served as explant sources and were cultured in Murashige and Skoog medium supplemented with plant growth regulators for 30 days. The highest callus induction rates were achieved in hypocotyls treated with 1.5 mg L^− 1 2,4-D, 1.0 mg L^− 1 BA with 1.0 mg L^− 1 2,4-D, or 0.5 mg L^− 1 TDZ. Cell suspension cultures were established from callus in medium supplemented with 0.5 mg L^− 1 TDZ. Growth kinetics analysis revealed a growth rate of 0.187 d^− 1 and a doubling time of 3.7 days. The maximum total phenol content in cell suspension extracts was 71.73&#xa0;mg GAE g^− 1 DW, which was 3-, 9-, and 17-fold higher than in leaves, seeds, and pulp of adult trees, respectively. Moreover, these extracts exhibited radical inhibition of 5.82 and 6.09 mmol TE g^− 1 DW for ABTS and DPPH radicals, respectively, similar to the values obtained for leaves and seeds of adult trees. UPLC-ESI-MS analysis of the extracts led to the identification of flavonoids, including naringenin, catechin, procyanidin, kaempferol, eriodictyol, and atrovenetinone. This study represents the first report on the establishment of in vitro cultures of <i>T. indica</i>, which can serve as a valuable source of phenolic compounds with strong antioxidant activity and diverse bioactivities, applicable in the pharmaceutical, nutraceutical, and food industries.</p>