Controlled polymerization through living radical polymerization is widely studied. Controlled polymerization enables synthetic polymers with precise structures, which have the potential for excellent bio-functional materials. This review summarizes the applications of controlled polymers, especially those via living radical polymerization, to biofunctional materials and conjugation with biomolecules. In the case of polymer ligands like glycopolymers, the polymers control the interactions with proteins and cells based on the precise polymer structures. Living radical polymerization enables the conjugation of polymers to proteins, antibodies, nucleic acids and cells. Those polymer conjugations are a sophisticated method to modify bio-organisms. The polymer conjugations expand the potential of biofunctional materials and are useful for understanding biology.