Background and Aims Research has found a close relationship between transmembrane protein (TMEM) family genes and tumors. TMEM201 is a member of the TMEM family, and its expression and role in hepatocellular carcinoma (HCC) are currently unclear. Therefore, this study was conducted, uses bioinformatics methods, to analyze the expression and function of TMEM201 in HCC and predict the pathways it may be involved in, exploring the underlying mechanisms.Methods TMEM201 expression in pan-cancer is analyzed using TIMER. Data of HCC patients from TCGA and GEO databases are downloaded, and the specimens and clinical information of 106 HCC patients were collected. The expressions of TMEM201 in liver cancer tissue and adjacent tissue were analyzed, the survival curves were plotted to analyze the relationship between TMEM201 expression and the prognosis of HCC patients. Univariate and multivariate Cox analyses are employed to identify HCC-related risk factors. The relationship between TMEM201 expression and clinicopathologic characteristics of HCC patients was analyzed based on TCGA and clinical data. String and GeneMANIA databases were used to construct a network diagram of TMEM201 and its related genes. TCGA database was used to analyze the relationship between TMEM201 and immune cells. LinkedOmics database was employed to analyze co-expressed genes related to TMEM201, followed by GO functional analysis and KEGG pathway prediction of these co-expressed genes.Results Pan-cancer analysis showed that TMEM201 was highly expressed in the majority of tumors. Multiple databases analysis and immunohistochemical results of clinical HCC specimens revealed that TMEM201 expression in HCC tissue was significantly higher than that in adjacent tissue (all P<0.05). Additionally, patients with high TMEM201 expression had a significantly shorter survival time than those with its low expression. Univariate and multivariate Cox regression suggested that TMEM201 expression was an independent risk factor for overall survival in HCC patients. Protein interaction networks and GeneMANIA database analysis showed significant interactions between TMEM201 and genes such as SUN1, SUN2, LMNB1, and EMD. Immune infiltration analysis indicated a significant association between TMEM201 expression and dendritic cells, cytotoxic cells, Th2 cells, etc. Furthermore, functional enrichment analysis demonstrated that TMEM201 and its co-expressed genes were involved in various biological processes, cellular components, molecular functions, and signaling pathways related to HCC. Pathway results and correlation heatmaps suggested a strong correlation between TMEM201 and the cell cycle.Conclusion TMEM201 is highly expressed in HCC tissue and is an independent risk factor influencing the prognosis of HCC patients. The mechanism of action of TMEM201 in HCC may be related to the regulation of immune infiltration and the control of the cell cycle.