Objective: Of-late, there is an abundant usage of synthesized metal nanoparticles of silver, gold, platinum, etc. in the field of medicines and physics. As these nanoparticles are metal and when they are used as medicine for therapeutic purposes,they become toxic. Hence, a maiden attempt has been made for nanoparticle synthesization using phosphorous for avoiding metal. Here, the present study is about using the seed extract of Caesalpinia bonducella synthesized phosphorous nanoparticle (PNPs) for the first time, that an eco-friendly manner. Methods: The PNPs were synthesized using Caesalpinia bonducella seed extracts and the synthesized PNPs were characterized by ultraviolet (UV)–visible spectrophotometry, Fourier-transform infrared (FTIR) spectroscopy, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis. Results: Synthesis of nanoparticles was confirmed and ascertained by visual detection in which the orange coloured solution gets changed to a brown colour. Further, a combination of spectroscopic and microscopic techniques were used to characterize the synthesized nanoparticles via UV- Vis Spectroscopy, FTIR, XRD and SEM analysis. Significant absorption was observed at 279 nm resulting in the formation of nanoparticles. FTIR analysis was performed to identify the biomolecules, which played a key role in the reduction of phosphorous. The XRD and SEM result revealed a crystalline nature of PNPs. Conclusion: This approach has proven that PNPs can be synthesized by using seed extract in which biomolecules effectively act as capping and reducing agent.