Cancer is a multifactorial disease characterized by uncontrolled cell growth and a high mortality rate, making it one of the major global health challenges. Conventional therapies, such as chemotherapy, face significant limitations, including systemic toxicity and multidrug resistance, highlighting the need for new, more selective and effective therapeutic approaches. In this context, the lectin from Vatairea macrocarpa (VML), a protein with specific affinity for carbohydrates such as galactose and N-acetylgalactosamine, has shown promising biological activity against tumor cells. Studies indicate that VML selectively interacts with Tumor Associated Carbohydrates (TACs) present on the surface of cancer cells, inhibiting processes such as cell proliferation, angiogenesis, and metastasis. This study investigates VML, analyzing its cytotoxicity in human tumor cell lines, its antiangiogenic potential, and its toxicity in Drosophila melanogaster. A soluble protein extract was obtained from V. macrocarpa seeds as an initial step for the purification of the lectin. After purification, in vitro and in vivo assays were conducted to evaluate the biological properties and therapeutic potential of the isolated lectin. The results showed that VML exhibited significant selective cytotoxicity in tumor cells. In leukemia cell lines, VML inhibited cell growth with IC50 values ranging from 3.5 to 102.0 µg/mL, for HL-60 (acute promyelocytic leukemia) and KG1 (acute myeloid leukemia), respectively, while it was non-toxic to non-tumor cells such as HaCat and VERO. VmL inhibited 73.79% of A549 cells (lung cancer) with an IC50 of 97.21 µg/mL, without effects on other tumor cell lines or normal cells. In the CAM model, VML exhibited a strong antiangiogenic effect, reducing A549-induced vascularization by 70.38% in a concentration dependent manner, and inhibiting angiogenic factors VEGF (71.07%) and TGF-β (65.97%). Immunohistochemistry confirmed the reduction in neovascularization and structural changes in the chorioallantoic membrane, such as a decrease in fibroblasts and inflammatory cells. In the D. melanogaster model, no toxicity was observed, suggesting that VmL is a promising molecule for in vivo studies. Thus, the lectin's unique ability to interact with specific carbohydrates on the cell surface may contribute to its selective antitumor effects, offering a potential alternative or complement to existing cancer therapies.