Growth factor-induced proliferation and differentiation often require adhesion of cells to the extracellular matrix proteins such as fibronectin (FN). In this study, we aimed to investigate the effect of protein engineering of the keratinocyte growth factor 2 (KGF2) fused to the FN on the mitogenic activity of KGF2. The fusion protein (KGF2-FN10), which was expressed in Escherichia coli, showed significantly enhanced mitogenic activity of KGF2 on human keratinocytes. Moreover, KGF2-FN10 fusion protein showed significantly increased activity to differentiate keratinocytes from native KGF2. In conclusion, these results suggest that KGF2-FN10 fusion protein has certain advantages over native KGF2 and may offer a novel strategy to potentiate the therapeutic effect of KGF2.