Glycopolymers with a-galactose (a-Gal) and a-mannose (a-Man) were synthesized by means of living radical polymerization with a reversible addition-fragment chain transfer reagent, and the thin-layer formation of glycopolymers was investigated in terms of protein recognition abilities. Thiol-terminated glycopolymers formed a thin layer of about 2.5 nm in thickness on a gold substrate, and the glycopolymer thin layer showed specific interaction with sugar recognition proteins (lectins and Shiga toxins (Stxs)). The interactions were highly specific, and the signal-to-noise ratio of protein recognition was greater than 16. Glycopolymer-substituted gold nanoparticles (GNPs) also showed biorecognition abilities and protein-specific aggregation. The protein recognition abilities of the GNPs were also analyzed. The glycopolymer-substituted GNPs were utilized for signal amplification of surface plasmon resonance (SPR) to detect protein-saccharide recognition. The glycopolymer with a-Gal showed a strong interaction with Stxs according to SPR measurements, suggesting a possible application of a-Gal-substituted GNPs in Stx-1 biosensing.