Light-based hydrogel crosslinking is a new approach in rapid and high-resolution 3D printing; however, using this method in tissue engineering is challenging due to the toxicity of photoinitiators, their solvents, and their low efficiency. Herein, a novel, water-soluble photoinitiator with high efficiency in light-based 3D printing is introduced. Low-cost photoinitator, 2,4,6-trimethylbenzoylphenyl phosphinate, is converted into nanoparticles via a microemulsion method and dispersed in water. Cell toxicity assays were performed to prove that these nanoparticles are non-toxic and can be used in biomedical applications. Finally, the nanoparticles were utilized in the high-accuracy 3D printing of hydrogels. The results of this study indicate that these particles are potent to be used in bioprinting.