Porous graphene and graphene-silica microparticles containing titania nanoparticles were synthesized by emulsion-assisted self-assembly for the photocatalytic decomposition of methylene blue in an aqueous medium. After the mixed dispersion of graphene nanosheets and titania nanoparticles with or without silicic acid was prepared, the complex fluid was emulsified in a continuous oil phase to form tiny droplets that act as micro-reactors for the synthesis of porous photocatalytic particles, the morphology of which was three-dimensional spherical shapes with a number of irregular-shaped macropores. The three dimensional conductive graphene scaffolds greatly enhanced the photocatalytic activity of the porous particles due to the suppression of the recombination of electron-hole pairs generated from titania under UV light irradiation, and adsorption of dye molecules on graphene-silica scaffolds caused rapid removal of aqueous contaminants. Unlike previous reports, the kinetics of the photocatalytic decomposition reaction could not be explained by Langmuir-Hinshelwood kinetics, but the experimental data could be fitted well by the second- or third-order kinetics. This indicates that the removal rate of the pollutant could be enhanced by the supporting material. The removal efficiency of methylene blue was estimated as more than 95% when sufficient amount of the photocatalytic particles was used, implying that application to water treatment process will be possible.