At first, synthesis and characterization of a new core–shell magnetic nanomaterial, namely 4,4′-bipyridin-1-ium hydrogen sulfate grafted on chloropropyl functionalized silica gel-nano-Fe3O4 (BPHCSF), have been reported; the characterization has been done using EDS, FE-SEM, TEM, FT-IR, XRD, TGA and VSM analyses. Afterward, examining catalytic performance of BPHCSF for the solvent-free preparation of 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives from 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (2 eq.) and arylaldehydes (1 eq.) has been described. The products have been obtained in high yields and short reaction times, and the catalyst was successfully reused for three times without significant decrement of its catalytic activity.