Abstract: A method for scaled-up synthesis of medium-entropy and high-entropy nanoparticles (NPs) including alloys and ceramics on various substrates such as carbon, metal and glass. The method requires only two steps to synthesize these NPs, including loading metal salt precursors with equal molar ratio onto a support and irradiating the support by highly intense laser pulses in liquid at ambient atmosphere. The method ensures multiple (3˜9) atoms to combine without segregation regardless of their mutual solubility. The method can easily tailor the particle size from nanometer to micrometer by controlling the parameters.