A series of 1-ethyl-1′-arylmethyl-4,4′-bipyridinium compounds is synthesized, where the aryl is phenyl (BEV), 2-naphthyl (NEV), 2-anthracenyl (AEV) or 1-pyrenyl (PEV). Among them, PEV and AEV can bind with calf thymus DNA mainly through intercalation and groove-binding modes, and both of them can be observed to photocleave plasmid pBR 322 DNA significantly under irradiation with a xenon arc lamp. After inclusion of cucurbit[8]uril (CB[8]), all of the aromatic donor–viologen acceptor compounds exhibit efficient DNA photocleavage ability. The reason is that CB[8] can inhibit the intramolecular backwards electron transfer in the aromatic donor–viologen acceptor molecule, prolonging the lifetime of the charge separated excited state to some extent. These studies bring a new subject in DNA photocleavage research and a potential application of the host–guest supramolecular system.