The microenvironment for culturing of cells is important in tissue engineering and biomedical applications. Owing to their excellent biocompatibility, hydrogels are widely used to create microenvironments. One of the most useful hydrogels, gelatin methacryloyl (GelMA), can be cured by ultraviolet (UV) light to form a polymer. However, the use of a photoinitiator in this process results in cellular toxicity. In this study, we developed a novel method to polymerize GelMA hydrogel into desired patterns based on the principle of optically induced electropolymerization. For this technique, the polymer films were electrodeposited by optical virtual electrodes at the surface of a photoconductive substrate, instead of real conductive metallic electrodes. The shapes of the virtual electrodes depend on digitally projected images. The thickness of the deposited films, ranging from nanometers to micrometers, is controlled by the duration of the applied AC voltage. In this paper, we discuss the parameters used during the optically induced electropolymerization process to realize several microstructures of GelMA hydrogel with different shapes and sizes.