Background <p>Identifying patients at risk for VTE and stratifying that risk is critical to determine who will benefit from thromboprophylaxis. China’s clinical practice still faces limitations, particularly regarding systematic and practical VTE risk assessment tools for cancer patients. This study aims to develop and validate the CHIna’s Cancer-Associated venous Thromboembolism risk assessment tool (CHI-CAT score) compared to the Khorana score.</p> Methods <p>Cancer patients aged 18 or older hospitalized in the Third People’s Hospital of Chengdu from March 2022 to September 2023 were retrospectively involved in this study. The cohort was divided into two groups based on whether they experienced VTE. Patients with VTE were compared to those without VTE according to their Khorana and CHI-CAT scores, respectively. Model discrimination performance was comprehensively evaluated using the standard sensitivity, specificity, maximum approximate entry index, and the area under the receiver operating characteristic curve(AUC).</p> Results <p>Data from 868 patients were analyzed. The CHI-CAT score was developed from a derivation cohort (<i>n</i> = 428) and further assessed in the validation cohort (<i>n</i> = 440). The predictive threshold for the risk assessment tool was set at 8 points. The AUC of the CHI-CAT score was 0.808 (95% CI, 0.715–0.901), with a significance level of <i>P</i> &lt; 0.001. The verification results indicate that the AUC of the CHI-CAT and Khorana scores were 0.782 and 0.662, respectively, with a significance level of <i>P</i> &lt; 0.001. The sensitivity of these two models was 0.826 and 0.478, respectively, while the specificity was 0.640 and 0.751.</p> Conclusions <p>The CHI-CAT score has been developed and validated, demonstrating relatively comprehensive components and a predictive capability that exceeds the Khorana score. However, its reliability and validation need improvement through testing in larger internal and external retrospective cohorts.</p>