In this work, we have synthesized two polymer-grafted cation exchangers: one via the grafting-from approach, in which sulfopropyl methacrylate (SPM) is grafted through atom transfer radical polymerization onto Sepharose FF (the thus resulting exchanger is referred as Sep- -SPM), and another via the grafting-to approach, in which the polymer of SPM is directly coupled onto Sepharose FF (the thus resulting exchanger is called as Sep- SPM). Protein adsorption on these two cation exchangers have been also investigated. At the same ligand density, Sep- -SPM has a larger accessible pore radius and a smaller depth of polymer layer than Sep- SPM, due to the controllable introduction of polymer chains with the regular distribution of the ligand. Therefore, high-capacity adsorption of lysozyme and -globulin could be achieved simultaneously in Sep- -SPM with an ionic capacity (IC) of 308 mmol·L . However, Sep- SPM has an irregular chain distribution and different architecture of polymer layer, which lead to more serious repulsive interaction to proteins, and thus Sep- SPM has a lower adsorption capacity for -globulin than Sep- -SPM with the similar IC. Moreover, the results from protein uptake experiments indicate that the facilitated transport of adsorbed -globulin occurs only in Sep- SPM and depends on the architecture of polymer layers. Our research provides a clear clue for the development of high-performance protein chromatography.