The magnetic ionic liquid, tri(1-butyl-3-methylimidazolium) gadolinium hexachloride, ([bmim]3[GdCl6]), has been used as an efficient green catalyst for the one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles via the condensation of benzil, an aromatic aldehyde, aniline, and ammonium acetate. Good to excellent yield, mild reaction conditions, as well as ease of operation and work-up are some advantages of the protocol.