Despite the wide utility of gold nanorods (GNRs) in biomedical fields, only a few methods for modifying or coating the surface of GNRs suitable for biomedical applications are available. In this study, we report a new facile method that enables formation of an ultra-thin (nanometre-thickness) siloxane layer on GNRs with anti-biofouling properties and ligand functionalisation ability. A triblock random copolymer, poly(TMSMA-r-PEGMA-r-NAS), was used to coat GNRs. An ultrathin polymeric shell was formed surrounding GNRs through acid-catalysed crosslinking of silicates of TMSMA. The polymer-coated GNRs (p-GNRs) exhibited high colloidal stability in biological solutions of high ionic strength and long-term stability superior to that of PEG(2k)-S-GNRs. The functionalities of NAS were demonstrated using two methods for conjugating targeting ligands and loading doxorubicin via electrostatic interactions. The ligand-specific cancer-targeting ability and combinatorial chemo-photothermal anticancer effects were validated in vitro and in vivo, suggesting their potential utility in various fields.