In this study, a series of B-ring fluoro substituted bis-chalcone derivatives were synthesized by Claisen-Schmidt condensation reactions and evaluated for their ability to inhibit xanthine oxidase (XO) and growth inhibitory activity against MCF-7 and Caco-2 human cancer cell lines, in vitro. According to the results obtained, the bis-chalcone with fluoro group at the 2 (4b) or 2,5-position (4g) of B-ring were found to be potent inhibitors of the enzyme with IC50 values in the low micromolar range. The effects of these compounds were about 7 fold higher than allopurinol. The binding modes of the bis-chalcone derivatives in the active site of xanthine oxidase were explained using molecular docking calculations. Also, compound 4g and 4h showed in vitro growth inhibitory activity against a panel of two human cancer cell lines 1.9 and 6.8 mu M of IC50 values, respectively.