Dinizia Excelsa is an Amazonian tree with a wide range of applications as a raw material in the industry. The objective of this study was to extract, characterize, and evaluate the biological activities of xylan extracted from Dinizia excelsa wood. The xylan was obtained in five stages, including delignification, precipitation, purification, and freeze-drying. The physicochemical analysis of xylan included the determination of monosaccharides, elemental composition, FTIR analysis, 2D nuclear magnetic resonance spectroscopy, and the determination of molecular weight. Xylan had an extraction yield of 28.44% and an elemental composition of 35.03% carbon, 5.65% hydrogen, and 59.32% oxygen. FTIR analysis revealed similarities between Dinizia excelsa xylan and commercial xylan. 2D NMR analysis confirmed the presence of characteristic xylan groups. Furthermore, xylan has a low molecular weight. In vitro cytotoxicity tests demonstrated low toxicity, indicating its potential for biological applications. Immunomodulatory activity assays revealed that xylan stimulated cell proliferation and the production of anti-inflammatory cytokines. The anticoagulant activity of xylan was low compared to heparin. The antioxidant activity of xylan was weaker compared to ascorbic acid and butylated hydroxytoluene (BHT). These results indicate that xylan from Dinizia excelsa has potential for several biomedical applications due to its immunomodulatory and anticoagulant properties.