The plasmonic cerium vanadate (CeVO4) semiconductor and plasmonic silver (Ag) metal exhibit a localized surface plasmon resonance (LSPR) effect in the visible (Vis)-light region; however, weak absorption in the near-infrared (NIR) region restricts their environmental remediation and biomedical application. Herein, CeVO4/Ag nanohybrids with self-assembled heterostructure and improved Vis/NIR light absorption were synthesized from CeVO4 nanosheets and AgNO3 solution, which could serve as potential solar-driven catalytic agents and near-infrared (NIR) light responsive anticancer agents. Oleic acid-stabilized CeVO4 nanosheets were modified with the HS-PEG1000-OH by the thiol-ene click reaction and presented self-assembly morphology in aqueous solution due to hydrophobic-hydrophobic interactions. Sulfhydryl (-SH) groups provided stable sites for Ag+ ions on the surface of CeVO4, and Ag+ ions could be directly reduced by Ce3+ ions to form CeVO4/Ag heterojunction nanocrystals (NCs). Due to the higher absorption in the Vis/NIR light region than CeVO4 nanosheets, CeVO4/Ag NCs led to the improved solar light responsive photocatalytic degradation of organic dyes. Upon the exposure of these NCs to an 808 nm laser, CeVO4/Ag NCs show high photothermal conversion efficiency, ROS generation ability and photoacoustic (PA) signal for implementing PA imaging-guided photothermal/photodynamic synergistic cancer therapy with better tumor inhibition effect.