Tumor angiogenesis is a hallmark of cancer and is involved in the tumorigenesis of solid tumors. B7-H3, an immune checkpoint molecule, plays critical roles in proliferation, metastasis and tumorigenesis in diverse tumors; however, little is known about the biological functions and molecular mechanism underlying B7-H3 in regulating colorectal cancer (CRC) angiogenesis. In this study, we first demonstrated that the expression of B7-H3 was significantly upregulated and was positively associated with platelet endothelial cell adhesion molecule-1 (CD31) level in tissue samples from patients with CRC. In addition, a series of in vitro and in vivo experiments showed that conditioned medium from B7-H3 knockdown CRC cells significantly inhibited the migration, invasion, and tube formation of human umbilical vein endothelial cells (HUVECs), whereas overexpression of B7-H3 had the opposite effect. Furthermore, B7-H3 promoted tumor angiogenesis by upregulating VEGFA expression. Recombinant VEGFA abolished the inhibitory effects of conditioned medium from shB7-H3 CRC cells on HUVEC angiogenesis, while VEGFA siRNA or a VEGFA-neutralizing antibody reversed the effects of conditioned medium from B7-H3-overexpressing CRC cells on HUVEC angiogenesis. Moreover, we verified that B7-H3 upregulated VEGFA expression and angiogenesis by activating the NF-κB pathway. Collectively, our findings identify the B7-H3/NF-κB/VEGFA axis in promoting CRC angiogenesis, which serves as a promising approach for CRC treatment.