Hydrogels are promising platforms capable of mimicking the biocompatible extracellular matrix (ECM) environment for tissue engineering. Hydrogel-based cell scaffold has been developed in various applications using different morphology and fabrication method. Among them, photocrosslinkable hydrogel systems have been extensively studied due to their commercial potential based on fast and controllable crosslinking. These advantages offer rapid formation of precise structures for cell-based tissue therapy, such as bioprinting and cell encapsulation. But ultraviolet (UV) induced phototoxicity and cytotoxicity during photocrosslinking remain important issues for translating into the clinic. In this thesis, I aimed to design a new photocrosslinkable hydrogel system and suggest a fabrication method for cell-based tissue engineering therapies. To this end, new water-soluble visible light photoinitiators (PIs), lithium benzoyl(phenyl)phosphinate (BP), were synthesized, which were activatable in the visible regions to reduce UV-induced phototoxicity and offer fast photoreactivity. Also, it showed low cytotoxicity compared to commercial PIs. In addition, a bioink for bioprinting and an in-air photopolymerization platform for cell-laden microgel were developed using the new PI. This thesis is organized as follows.