This study is devoted to the investigation of the effect of laser radiation of different wavelengths (355, 527 and 1054 nm) on the morphology, structure and optical properties of platinum nanoparticles synthesized in a gas discharge. The results confirmed that all three types of lasers can be used to modify platinum nanoparticles and to change their sizes. The best modification that is shape transformation from aggregates to individual nanoparticles is achieved by using an infrared laser (1054 nm). It was shown that all obtained nanoparticles have a maximum of plasmon resonance in the ultraviolet region in the wavelength range from 200 to 300 nm, which is similar to the additionally simulated calculations based on the theory of Mie absorption spectra of monodisperse platinum particles with sizes from 5 to 120 nm.