Preparation of graphene has suffered from poor controllability of its lateral dimensions and the lack of sufficient fractionation technologies-the main barriers to its large-scale commercialization. This situation requires the development of an effective size fractionation strategy. Herein, the size-selective adsorption of graphene oxide (GO) onto positively charged spheres was developed as a novel size fractionation method. A critical lateral size of GO existed, above which physical adsorption was not stable, possibly because of the mechanical deformation involved. This scalable fractionation process easily produces well-dispersed GO sheets of relatively large lateral sizes, apart from the relatively small-sized GO sheets that are stably anchored onto the spherical particles. Moreover, this process is energy efficient and does not require any special equipment. This fractionation principle, size-selective adsorption, can be generalized to other various 2D nanomaterials.