In recent years, Prussian blue (PB)-based nanoagents have become a new platform in photothermal cancer treatment. However, there is little research for PB-based nanoagents to achieve synergistic phototherapy guided by multimodal imaging diagnosis and monitoring. Herein, a novel single wavelength near infrared (NIR) laser-induced magnetically targeted theranostic nanoplatform has been successfully designed and synthesized for the first time based on polydopamine (PDA)/aluminum phthalocyanine (AlPc)/bovine serum albumin (BSA) coated magnetic Prussian blue nanoparticles (FeO@PB NPs) for multiple imaging-guided combinatorial cancer therapy. The resultant multifunctional FeO@PB@PDA/AlPc/BSA nanocomposites show excellent stability and superparamagnetism, facilitating them to achieve superior photothermal therapy in physiological environments under magnetic guidance. In addition, the delivery vehicles can remarkably increase tumor accumulation of AlPc, thus leading to an enhanced photodynamic therapy efficacy. Furthermore, FeO@PB@PDA/AlPc/BSA can be utilized as a multimodality nanoprobe for simultaneous diversified imaging, including near-infrared fluorescence imaging (NIRFI), magnetic resonance imaging (MRI), and photoacoustic imaging (PAI). Most importantly, without noticeable dark toxicity, the obtained FeO@PB@PDA/AlPc/BSA nanocomposites are able to significantly suppress tumor growth via combined photothermal and photodynamic therapies upon a single 660 nm laser irradiation, achieving a superior synergetic manner compared to monotherapy both in vitro and in vivo. Therefore, our strategy provides FeO@PB@PDA/AlPc/BSA nanocomposites for trimodality cancer imaging-guided synergistic therapy, with a great potential for new generation theranostics nanoagents.