Large-scale periodic arrays of iron oxide nanomaterials with controllable size and spacing are fabricated on solid substrates using block copolymer supramolecular assembly. The shape, size, and periodicity of the nanomaterials is tailored by altering the block copolymer composition, stoichiometry of the small molecules, and thickness of the film, whereas the crystal structure is controlled by the post-treatment of the block copolymer supramolecular thin film.