Nanoparticles with both efficient light emission and strong magnetization (MFSNPs) are fabricated by one-pot, surfactant-free sol–gel reaction of tetraethoxysilane and silole-functionalized siloxane in the presence of citrate-coated magnetite nanoparticles. The MFSNPs are uniformly sized with smooth surfaces. They possess core–shell structures and exhibit appreciable surface charges and hence good colloidal stability. The MFSNPs are superparamagnetic, exhibiting no hysteresis at room temperature. UV irradiation of the suspension of MFSNPs in ethanol gives strong green emission at 486 nm, thanks to the novel aggregation-induced emission characteristics of the silole aggregates in the hybrid nanoparticles. The MFSNPs can selectively stain the cytoplasmic regions of the living cells. Addition of (3-aminopropyl)triethoxysilane during the fabrication of MFSNPs has generated MFSNP-NH2 with numerous amino groups decorated on the surface, enabling the nanoparticles to immobilize bovine serum albumin efficiently.