In this study, novel SO3H-dendrimer functionalized magnetic nanoparticles (Fe3O4@Dsingle bondNHsingle bond(CH2)4single bondSO3H) were prepared and characterized by using FT-IR, X-ray diffraction patterns, scanning electron microscopy, transmission electron microscopy, thermogravimetry analysis, and energy-dispersive X-ray spectroscopy. The synthesized nanosized catalyst was successfully applied to the synthesis of highly substituted pyrans and polyhydroquinolines via a straightforward one-pot multicomponent condensation reaction. The key advantages are the short reaction time, high yields, simple workup, and purification of products by simple recrystallization from ethanol.