A facile approach was established for fabricating photothermo-responsive nanogels for simultaneous optical temperature-sensing, cell imaging, and combined chemo-photothermal treatment. The strategy for preparing the hybrid Au@IPN-pNIPAAm nanogels involved two steps, consisting of growing an acrylamide monolayer on a single gold nanoparticle, followed by in situ polymerization and crosslinking of N-isopropylacrylamide and acrylamide. The hybrid Au@IPN-pNIPAAm nanogels exhibited not only biocompatibility at low concentration <200 μg ml⁻¹, but also good function on cellular imaging by using dark-field microscopy. Furthermore, the integration of the unique scattering properties of AuNP core and the reversible thermo-responsive volume phase transition of IPN-pNIPAAm shell could offer a thermo-/photo-triggered release of a model anticancer drug 5-fluorouracil from Au@IPN-pNIPAAm nanogels. Hence, the hybrid Au@IPN-pNIPAAm nanogels, may offer broad opportunities for combined diagnosis and therapy.