Phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), has attracted great attention because it can effectively inhibit the proliferation and propagation of cancer cells. Recently, heterojunction nanomaterials have shown tremendous application value in the field of biological medicine. In this work, the CeVO₄/Au heterojunction nanocrystals (NCs) are designed for photothermal/photoacoustic bimodal imaging-guided phototherapy. The as-synthesized hydrophobic oleic acid (OA)-stabilized CeVO₄ nanosheets were modified with HS-PEG-OH for translating into hydrophilic ones, which can significantly improve their stability and biocompatibility. Subsequently, the plasmonic Au nanoparticles were in situ successfully deposited on the surface of HS-PEG-coated CeVO₄ to form CeVO₄/Au heterojunction NCs for improving the visible and near-infrared light absorption, which results in enhanced photothermal conversion performance and reactive oxygen species (ROS) generation capacity. Thus, the CeVO₄/Au can cause more severe damage to cancer cells than pure CeVO₄ under NIR laser irradiation. Also, CeVO₄/Au can provide distinct tumor contrast by photothermal/photoacoustic bimodal bioimaging. Our results demonstrate that CeVO₄/Au NCs could be used as an effective theranostic anticancer agent for near-infrared (NIR) light-mediated PTT and PDT.