Multifunctional nanoagents have become popular and valuable pharmaceuticals for effective cancer treatment. Moreover, there is an increasing tendency to develop therapeutic agents with excellent biocompatibility, high efficiency, specific targeting and combinatorial treatment effects. In this study, we proposed a facile technique to synthesize PEGylated (polyethylene glycol modified) magnetic Prussian blue (PB) nanoparticles with encapsulated doxorubicin (DOX), abbreviated as FeO@PB/PEG/DOX NPs, for combined targeted photothermal ablation and pH-triggered chemotherapy of tumour cells. The PEGylation of FeO@PB core-shell structure was achieved through a thin-film hydration process; DOX was loaded into the nanocapsule via hydrophobic interactions. An in vitro study indicated increased drug release under acidic conditions, mimicking mild acidic tumour microenvironments. Additionally, the nanocomposites exhibited superparamagnetism, contributing to an improved therapeutic effect guided by a localized magnetic field. Cytotoxicity studies demonstrated outstanding photothermal-chemotherapy combinatorial effects on HeLa cells, attributed to the targeted photothermic effect mediated by the pH-triggered cellular uptake of DOX. Specifically, the viability of HeLa cells decreased to 8.5% after treatment with the nanoagent (DOX=10μgmL) and near infrared irradiation, indicating an evident tumour inhibition effect in vitro. This study presented a nanoplatform for efficient and targeted cancer treatment, which may lead to the development of multifunctional nanodrug vehicles for cancer therapy.