A four-component reaction of phenylhydrazines, ethyl acetoacetate, aldehydes and β-naphthol has been achieved in the presence of FeCl3/SiO2 nanoparticles as a highly effective heterogeneous catalyst to produce 2-aryl-5-methyl-2,3-dihydro-1H-3-pyrazolones in good to excellent yields, short reaction times, mild reaction conditions and the employment of a cost-effective catalyst.