The title compound, C18H14ClN3O2, was synthesized by the condensation of 2-chloro-5-nitrobenzaldehyde with 2-methyl-1-propenylbenzimidazole, and the molecule comprises a 2-chloro-5-nitrobenzene and a 1-(Z)-propenylbenzimidazole. The two aromatic moieties are conjugated through the vinyl group. The dihedral angle between the two rings is 1.4(6) degrees. The propenyl group lies out of the benzimidazole plane with a dihedral angle of 112.9(9) degrees.