Artificial nanoreactors that can facilitate catalysis in living systems on-demand with the aid of remotely operable and biocompatible energy-source, are needed to leverage the chemical diversity and expediency of chemical synthesis in biology and medicine. Here, we designed and synthesized plasmonically-integrated nanoreactors (PINERs) with highly tunable structure and NIR-light-induced synergistic function for efficiently promoting unnatural catalytic reactions inside living cells (Figure 1). We devised synthetic approach towards PINERs by investigating the crucial role of metal-tannin coordination polymer nanofilm — the pH-induced decomplexation-mediated phase-transition process — for growing arrays of Au-nanospheroid-units, constructing a plasmonic corona around the proximal and reactant-accessible silica-compartmentalized catalytic nanospace. Owing to the extensive plasmonic coupling effect, PINERs show strong and tunable optical absorption in NIR-range, ultrabright plasmonic light scattering, controllable thermoplasmonic effect and remarkable catalysis; and, upon internalization by cells, PINERs are highly biocompatible and demonstrate dark-field microscpy-based bioimaging features. Empowered with the synergy between plasmonic and catalytic effects and reactant/product transport, facilitated by the NIR-irradiation, PINERs can perform intracellular catalytic reactions with dramatically accelerated rates and efficiently synthesize chemically activated fluorescence-probes and anticancer drugs inside living cells. In future, PINERs can be advanced to the development of highly selective targeted theranostic platforms switchable in the response to the variety of designer biorthogonal catalytic reactions. Reference: Kumar, A. et al. ACS Catal., 2019, 9, 977–990.