Introduction: Tamarind seeds are by-products generated during the production of candies and beverages. The seeds of Tamarindus indica L. contain tamarind seed gum, a polysaccharide extracted from the endosperm. This gum has potential applications in pharmaceutical, cosmetic, food, paper and textile industries, among others.  Aim: To characterize the chemical composition and functional properties of T. indica seed gum obtained as an industrial by-product. Methods: The biopolymer was extracted using an aqueous method at 70°C for 1.5 h. For compositional analysis, ash content was determined at 800°C, and moisture content was assesed by loss on drying at 105°C. Protein and carbohydrate contents were quantified using the Bradford assay and phenol-sulfuric acid method, respectively. The identity of the biopolymer was confirmed by Fourier-transform infrared (FTIR) spectroscopy. Antioxidant activity was evaluated using the ABTS and DPPH assays, while prebiotic potential was assessed based on the growth of Weisella paramesenteroides in tryptic soy broth (TSB) at 36 °C. Viscosity measurement was performed using a Brookfield viscometer equipped with spindle No. 2 using a 1% w/v aqueous solution (100 rpm, 25  °C).Data analysis was conducted using OriginPro software, and results are presented as mean ± standard deviation. Results: The FTIR spectrum confirmed that the extracted biopolymer corresponds to xyloglucan. On a dry basis, its chemical composition comprised carbohydrates (88.6 ± 0.4 %), proteins (1.0 ± 0.1 %), and ash (1.1 ± 0.1 %). The gum exhibited antioxidant activity in both ABTS and DPPH assays. Furthermore, its prebiotic potential was demonstrated by the stimulation of W. paramesenteroides growth, a lactic acid-producing bacterium. At a 1% concentration in aqueous solution, the viscosity was determined to be 117.5 ± 0.70 cP. Conclusion: Tamarind seed, an agro-industrial by-product, is a viable source of xyloglucan. The extracted biopolymer displayed a purity of approximately 90% and exhibited functional properties, including viscosity-enhancing, antioxidant, and prebiotic activities. These findings support its potential application in the food and biomedical industries.