Here a multifunctional nanoplatform (upconversion nanoparticles (UCNPs)-platinum(IV) (Pt(IV))‒ZnFeO, denoted as UCPZ) is designed for collaborative cancer treatment, including photodynamic therapy (PDT), chemotherapy, and Fenton reaction. In the system, the UCNPs triggered by near-infrared light can convert low energy photons to high energy ones, which act as the UV–vis source to simultaneously mediate the PDT effect and Fenton's reaction of ZnFeO nanoparticles. Meanwhile, the Pt(IV) prodrugs can be reduced to high virulent Pt(II) by glutathione in the cancer cells, which can bond to DNA and inhibit the copy of DNA. The synergistic therapeutic effect is verified in vitro and in vivo results. The cleavage of Pt(IV) from UCNPs during the reduction process can shift the larger UCPZ nanoparticles (NPs) to the smaller ones, which promotes the enhanced permeability and retention (EPR) and deep tumor penetration. In addition, due to the inherent upconversion luminescence (UCL) and the doped Yb and Fe in UCPZ, this system can serve as a multimodality bioimaging contrast agent, covering UCL, X-ray computed tomography, magnetic resonance imaging, and photoacoustic. A smart all-in-one imaging-guided diagnosis and treatment system is realized, which should have a potential value in the treatment of tumor.