N-Phenylglycine is normally used as a co-initiator and can be photodecomposed by different dyes under UV or visible light irradiation to generate radicals for the initiation of free radical photopolymerization. However, the photochemistry and photoinitiation ability of N-phenylglycine alone upon exposure to near-UV light (e.g., UV LED at 392 nm), to the best of our knowledge, have not been investigated. In this research, the photochemistry of N-phenylglycine under the UV LED at 392 nm is studied using various approaches, and it reveals that radicals (PhNHCH2•) can be produced from the direct photodecomposition of N-phenylglycine. In addition, N-phenylglycine can also interact with iodonium salt under the UV LED at 392 nm to generate phenyl radicals and cations. These formed active species exhibit high performance to initiate the free radical photopolymerization of acylates and cationic photopolymerization of epoxides and divinyl ethers.