Highly ordered macroporous materials with uniform pore size of the micrometer scale are known to have important technological uses such as photonic band-gaps and optical stop-bands. However, they can only be produced through adequate treatment of ordered monodisperse macroemulsions. Here, we report how a small amount of a new polymeric emulsifier leads to the rapid formation of a crystalline array of oil cells surrounded by a thin layer of aqueous polymer solution using a simple shear in-situ emulsification procedure. The three-dimensional periodic structure is demonstrated by Bragg diffraction and optical microscopy.