In this work, a new heterogeneous catalyst based on 1,2,3‐triazole complex of copper supported on core–shell Fe3O4@SiO2 nanoparticles was designed and characterized by using several methods such as infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetry analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy‐dispersive X‐ray spectroscopy (EDX). The magnetic nanocatalyst was successfully employed for the synthesis of different functionalized 3,4‐dihydropyrimidin‐2(1H)‐ones/thiones by a one‐pot multicomponent condensation reaction under solvent‐free conditions. Among the advantages of the developed catalytic protocol are the high yields, short reaction times, ecofriendly, easy workup and purification conditions.