B7 homologue 6 (B7-H6) is a new member of the B7 family molecules and is selectively expressed on tumor cells, especially in hematologic malignancies. However, the role of B7-H6 in lymphoma progression and chemosensitivity remains unclear. We determined the effects of downregulating B7-H6 expression on tumorigenesis and chemosensitivity in B-cell lymphoma. Stable B7-H6 knockdown in CA46 cells was established with a lentiviral system. The expression of mRNA was measured by PCR while protein expression was detected by western blotting and flow cytometry. Cell viability, apoptosis and cell cycle distribution were analyzed using CCK-8, colony formation and flow cytometry assays, respectively. Cell migration and invasion were determined using the Transwell chamber assay. B7-H6 was widely expressed in B-cell lymphomas. Knockdown of B7-H6 inhibited cell proliferation, colony formation and migration and invasion of lymphoma cells. After B7-H6 silencing, CA46 cells were arrested in G0/G1 phase. Moreover, the silencing of B7-H6 increased cell apoptosis and sensitivity to vincristine and dexamethasone. Investigation of expression of downstream targets of STAT3 supported a theory in which B7-H6 knockdown may confer an antitumor effect via abrogation of the STAT3 pathway. This study demonstrates that B7-H6 plays an important role in the pathogenesis and chemosensitivity of lymphoma. B7-H6 is therefore a potential clinical biomarker and therapeutic target in B-cell lymphomas.