Used primarily in organic synthesis, 1-Phenyl-3-guanylthiourea serves as a key intermediate in the production of various pharmaceuticals. It is particularly valuable in the development of antithyroid agents, which are crucial for managing hyperthyroidism. Additionally, this compound is employed in the synthesis of herbicides, aiding in the control of unwanted vegetation in agricultural settings. Its role in the creation of dyes and pigments also makes it significant in the textile and printing industries. Furthermore, it is utilized in research laboratories for studying biochemical pathways and enzyme inhibition mechanisms.