Prenylated stilbenoids are known for their unique health benefits and have been found to exhibit strong α-glucosidase inhibitory activities. In this study, the dimethylallylation of eight stilbenoids was investigated, which was catalyzed by engineered enzymes of the fungal prenyltransferase AnaPT. These reactions of stilbenoids catalyzed by AnaPT_F265D and AnaPT_F265G are chemo-selective and 17 products are all C-dimethylallylated stilbenoids, including twelve mono- and five di-dimethylallylated stilbenoids, significantly expanding the structure diversity of naturally occurring dimethylallylated stilbenoids. 10 Compounds were reported for the first time in this study. The molecular docking of 1D1 with AnaPT was also conducted, which revealed that N115 was likely a key residue. Our results showed that the catalytic efficiencies of AnaPT_F265D_N115K and AnaPT_F265D_N115A were higher than the other mutants obtained. Eight compounds (1D1, 2D1, 3D2-3D4, 6D1, 6D4, and 8D1) exhibited inhibitory effects on α-glucosidase with IC