Diethyl phenylphosphonate is widely used as a key intermediate in the synthesis of various organophosphorus compounds. It plays a significant role in the production of flame retardants, which are incorporated into materials like plastics, textiles, and electronics to enhance fire resistance. Additionally, it is utilized in the preparation of pharmaceuticals, particularly in the development of antiviral and anticancer agents, where it acts as a building block for complex molecules. In agriculture, it serves as a precursor for the synthesis of pesticides and herbicides, contributing to crop protection. Its application also extends to the field of organic chemistry, where it is employed in catalytic reactions, as a reagent in the Horner-Wadsworth-Emmons olefination for forming carbon-carbon double bonds, and in the formation of carbon-phosphorus bonds.