Abstract: B7-H3, a member of the B7 family within the immunoglobulin superfamily, is aberrantly expressed in tumor tissues and can be induced by immune cells, but is minimally expressed or not expressed in normal tissues. B7-H3 has gained attention for its ability to induce malignant behaviors in tumors and promote cancer progression through various complex pathways. Immunotherapy targeting B7-H3 has shown significant efficacy in clinical trials by modulating the immune system to enhance anti-tumor immune responses. We comprehensively summarize the abnormal expression and impact of B7-H3 in various human tumor types, and its role in immunotherapy, highlighting recent advances in clinical research targeting B7-H3. These findings suggest that B7-H3 holds great value as a future target for cancer diagnosis and treatment.