AbstractWe describe the immobilization of histidine‐tagged green fluorescent protein (His6‐GFP) specifically and reversibly onto single‐walled carbon nanotubes (SWCNTs) using nickel complexed nitrilotriacetic acid‐end functionalized polystyrene (Ni‐NTA‐PS) by conjugation between the protein and the polymer in phosphate buffer solution (PBS). We synthesized Ni‐NTA‐PS by atom transfer radical polymerization (ATRP) using a nitrilotriacetic acid (NTA) initiator. The SWCNTs were dispersed in PBS along with Ni‐NTA‐PS and His6‐GFP aided by sonication. The diameter of the dispersed SWCNTs was measured by transmission electron microscope (TEM). The immobilization of His6‐GFP and dispersion of SWCNTs were controlled by addition of excess imidazole. It was found that the immobilized His6‐GFP was more stable than free His6‐GFP in organic solvent (PBS/DMF, 1/1, v/v).