We report here a novel protein sequestration method using polymeric colloidal particles prepared by emulsion polymerization with reactive block copolymers. Specifically, poly(4-vinyl-N-ethylpyridine bromide)-block-polymethylacrylate block copolymers were synthesized from reversible addition-fragmentation chain transfer polymerization and used as emulsifiers for emulsion polymerization of poly(4-vinyl-N-ethylpyridine bromide)-functionalized polymeric colloidal particles. The particles have high and stable zeta potentials when dispersed in solution, regardless of pH variations. As a result, the polymeric colloids demonstrate a high affinity for oppositely charged proteins, even though the isoelectric points of proteins may vary greatly. We show here that BSA can be sequestered highly efficiently with a maximum binding capacity (~900 mg/g). The adsorbed protein is easily released, and the polymeric colloids are regenerated after washing with a buffer solution of high ionic strength. These properties may prompt this type of novel macromolecule-functionalized colloids to be utilized for effective protein adsorption and separation.