Bioinspired copolymers consisting of a glycopolymer main chain grafted with polylysine were synthesized using metal-free click chemistry based on a 1,3-dipolar cycloaddition reaction involving strained cyclic alkyne. Poly(2-deoxy-2-methacrylamido-d-glucose)-graft-polylysine was efficiently complexed with a double-stranded oligonucleotide duplex. The cytotoxicity of the polyplex was lower than that of the free copolymer.