Inorganic metal halide perovskites CsPbX3 (X = Cl, Br, and I) has achieved extensive attention in recent years for photovoltaics because of their unique properties like tunable band gap, high charge carrier mobility, high absorption coefficient, etc. and which makes it suitable for optoelectronic applications. In this work, we have reported a facile synthesis method of inorganic CsPbBr3 nanoparticles (NPs) at room temperature using cesium bromide (CsBr) as a Cs source, lead bromide (PbBr2) as Br source, oleic acid, and Oleylamine as capping ligands. Nucleation starts immediately after the injection of a precursor solution into the toluene. Synthesis of CsPbBr3 NPs was confirmed by X-Ray diffraction pattern, UV-Visible spectroscopy, photoluminescence (PL), scanning electron microscopy (SEM), and atomic force microscopy (AFM). X-ray diffraction pattern reveals mainly the monoclinic crystal structure of CsPbBr3 NPs. The UV-Vis absorption spectra and PL spectra show a strong absorption peak at 509 nm, emission peak at 505 nm, and the band gap of CsPbBr3 to be 2.2 eV. The synthesized CsPbBr3 exhibit regular cuboid like structure with a particle size of approximately 400-500 nm. The surface roughness morphology of CsPbBr3 NPs was studied using AFM, and it shows the roughness of the CsPbBr3 films was around 260 nm. These results provide a facile synthesis method, and CsPbBr3 NPs are a suitable candidate for the optoelectronic and photovoltaic device’s application.