henylazo]‐indazole}‐hexyl methacrylate)‐b‐poly(2‐(dimethylamino)ethylmethacrylate) (PDHMAm‐b‐PDMAEMAn), were successfully prepared via reversible addition‐fragmentation chain transfer polymerization technique. The homopolymer and amphiphilic diblock copolymer in CH2Cl2 exhibited intense fluorescence emission accompanied by trans–cisphotoisomerization of azoindazole group under UV irradiation. The