A phosphorus allotrope called greenish phosphorus was successfully synthesized via a simple chemical vapor deposition method. We revealed that the critical factors in the formation mechanism of greenish phosphorus are the partial pressure of the phosphorus vapor and the structure of the substrate. On the substrates of a glassy carbon wafer and carbon paper, the edge carbon structure can activate P4 molecules, allowing them to polymerize due to strong adsorption (Ead = -1.62 eV). Greenish phosphorus possesses a distinct crystal structure, different from red phosphorus and black phosphorus, thus leading to unique physical and chemical properties, and potential applications in optical, electrical, and magnetic fields.