Redox-active cytochrome b₅₆₂ with a tethered azide group on the heme propionate side chain is covalently linked to an acetylene moiety introduced on the sidewall of a single-walled carbon nanotube (SWNT) by copper-catalyzed click chemistry forming a triazole ring with the heme active site directly linked to the SWNT. The cytochrome b₅₆₂–SWNT hybrid is characterized by electrochemistry and atomic force microscopy.