Diphenyl phosphoramidate is primarily used as a flame retardant in various polymer materials, enhancing their resistance to ignition and combustion. It is particularly effective in applications involving thermoplastics and thermosetting resins, where it helps to meet stringent fire safety standards. Additionally, it serves as an intermediate in organic synthesis, playing a role in the production of pharmaceuticals and agrochemicals. Its ability to act as a phosphorylating agent makes it valuable in modifying biological molecules, contributing to the development of novel compounds with specific functionalities.