Immune cell infiltration in liver hepatocellular carcinoma (LIHC) is promising for immunotherapy. However, effective predictive markers to accurately predict a tumour's immune status are lacking. PSMD13, a native component of the 26 S proteasome subunit involved in intracellular metabolism, has an unclear association with cancer and immunity. Using bioinformatics analysis of data from the TCGA, we investigated the expression patterns, prognostic values, gene functions, and tumour immune relationships of PSMD13 in LIHC. We developed a prognostic model that incorporates PSMD13 for LIHC and validated the biological functions of PSMD13 in LIHC cells. Furthermore, we analysed the associations between PSMD13 expression and the tumour immune markers CD206 and CD8 in 101 paired liver tissues using immunohistochemistry. PSMD13 was upregulated in LIHC and served as a prognostic biomarker of LIHC. The knockdown of PMSD13 significantly affected the proliferation, migration, and colony formation of LIHC cells. PSMD13 was closely associated with the infiltration of M2 macrophages and the expression of various tumour immune checkpoints. Our study revealed that PSMD13 is a crucial component contributing to the malignant behaviour of LIHC, indicating its essential role in both the prognosis and potential immune microenvironment profile of LIHC.