Thermo-responsive block copolymer brushes of PNIPAM-b-P(MQ-co-GMA) were successfully grafted from graphene oxide (GO) by consecutive reversible addition–fragmentation chain transfer (RAFT) polymerization based on the monomers of N-isopropylacrylamide (NIPAM), 5-(2-methacryloyl-ethyloxymethyl)-8-quinolinol (MQ) and glycidyl methacrylate (GMA). The 8-hydroxyquinoline units in the polymer brushes could coordinate with Al³⁺ to form green luminescent copolymer brushes containing tris(8-hydroxyquinoline)aluminum (Alq₃) on the GO surface. The resulting fluorescent hybrid could be used as a nano-platform for the sensitive and robust detection of 2,4,6-trinitrophenol (TNP). The green fluorescence of the polymer brush modified GO hybrid in aqueous solution could be quenched by TNP via charge transfer and the observed linear fluorescence intensity change allowed the quantitative detection of TNP with a detection limit down to 2.38 × 10⁻⁹ M. The fluorescent nanohybrids exhibited a robust temperature-responsive behavior as a result of the conformation change in PNIPAM chains of polymer brushes.