Background and aimsTumor recurrence significantly affects the prognostic outcomes for liver cancer patients following liver transplantation. However, existing predictive models often neglect the inclusion of body composition indicators. Hence, this research aimed to investigate the significance of the psoas muscle index (PMI) in evaluating the post-transplant prognosis of liver cancer. MethodsA retrospective analysis was conducted on liver cancer patients who underwent liver transplantation surgery. Imaging analysis was performed using CT data to calculate PMI based on the left and right psoas muscle areas. Subsequently, the patients were categorized into PMI-Low and PMI-High groups using the established cut-off values. Univariate and multivariate analyses were performed using Cox proportional hazards regression to assess the correlation between PMI and clinical outcomes, and a nomogram was constructed accordingly. ResultsAmong the 225 patients included in the analysis, the PMI-High group exhibited significantly improved overall survival (P < 0.001) and disease-free survival (DFS, P < 0.001) rates compared to the PMI-Low group. PMI exhibited a positive correlation with body mass index (R = 0.25, P < 0.001), but no significant correlations were observed. In the multivariate analysis, PMI (HR = 4.596, P < 0.001), MELD score (HR = 1.591, P = 0.038), and Hangzhou criteria (HR = 2.557, P < 0.001) emerged as significant predictors of DFS. The constructed nomogram, incorporating these predictors, demonstrated outstanding predictive performance. Decision curve analysis revealed the superiority of the nomogram over conventional methods. ConclusionsPMI serves as a valuable prognostic factor for tumor recurrence in liver cancer patients after liver transplantation. The established nomogram is pivotal in delivering personalized predictions of DFS.