Encapsulating proteins in hydrogels has wide applications in drug release and tissue scaffolds modifications. In this paper, an optically-induced electropolymerization technique for patterning immunoglobulin G/polyethylene glycol diacrylate (IgG/PEGDA) hydrogels is reported. First the mechanism of optically-induced electropolymerization of PEGDA hydrogels is investigated. Then the electropolymerization of pure PEGDA and IgG/PEGDA hydrogels are experimentally verified respectively. The experimental results indicate that the reported technique can manufacture protein-encapsulated hydrogels with different geometry shapes, through using optical images designed by computer, alternating electrical field, and solution with hydrogel molecules and proteins. The cross-section shapes of the hydrogels are controlled by the optical images, the height of the hydrogels becomes increased with the increase of the deposition time. The smallest size of the manufactured structures is 3~4 μm. This technique makes possible the manufacture of tubular and high depth/width-ratio hydrogel microstructures, which is hard to imagine with the traditional manufacture methods.