Designed polymer hydrogel nanoparticles (NPs) capable of facilitating resolubilization and refolding of an aggregated protein, positively charged lysozyme, are prepared. NPs designed to interact strongly with denatured lysozyme and relatively weakly with native lysozyme, facilitated resolubilization and refolding of aggregated lysozyme. Such NPs could be prepared by copolymerizing optimized combinations and populations of functional monomers. The refolded lysozyme showed native conformation and enzymatic activity. Eleven grams of aggregated protein was refolded by 1 g of NPs. However, NPs having low affinity to denatured lysozyme and NPs having high affinity to both denatured and native lysozyme showed relatively low facilitation activity. Our results suggest a potential strategy for the design of artificial chaperones with high facilitating activity.