Background: Tungsten disulfide (WS2), which enjoyed a good potential to be a promising clinical theranostic agent for cancer treatment, is still subject to the tedious synthesis procedure. Methods: Here, we reported a one-pot 'bottom-up' hydrothermal strategy for the fabrication of PEGylated WS2 nanoparticles (NPs). The WS2-PEG nanoparticles were characterized systematically. The CT imaging and photothermal therapy against tumor as well as biosafety in vitro and in vivo were also investigated. Results: The obtained WS2-PEG NPs enjoyed obvious merits of good solubility and favorable photo thermal performance. WS2-PEG NPs exhibited desirable photothermal ablation ability against cancer cells and cancer cell-bearing mice in vitro and in vivo. MTT assay and histological analysis demonstrated the low cytotoxicity and biotoxicity of WS2-PEG NPs, providing a valid biosafety guarantee for the coming biomedical applications. In addition, thanks to the obvious X-ray attenuation of W atom, the WS2-PEG NPs can also be served as a favorable contrast agent for Cr imaging of tumors. Conclusion: WS2-PEG NPs has enjoyed a good potential to be a promising clinical CT-guided photo thermal therapeutic agent against cancers. (C) 2019 Published by Elsevier Inc.