Novel phosphinite functionalized magnetic (Fe3O4) nanoparticles having silica nanoshells containing an imidazolium ionic liquid moiety have been successfully synthesized and used as a support and stabilizer for palladium nanoparticles. The obtained compound was characterized by SEM, TEM, EDX, solid UV, VSM, XRD, XPS, FT-IR, and N2adsorption–desorption analyses. This magnetic composite has been applied as the catalyst in the Suzuki–Miyaura coupling reaction of aryl halides (I, Br, Cl) with arylboronic acids in aqueous media under mild reaction conditions and low palladium loading. The air stable catalyst could be easily separated from the reaction mixture using an external magnet and reused eight consecutive times with small drops in its catalytic activity.