Transmembrane proteins (TMEMs) are frequently used as prognostic biomarkers for various cancer types, making them a significant area of interest in cancer research. The prognostic significance of transmembrane protein 14C (TMEM14C) and its association with tumor-infiltrating immune cells (TIICs) has not been explored in liver hepatocellular carcinoma (LIHC). This study aimed to assess the potential prognostic value of TMEM14C by conducting a comprehensive analysis of online databases on LIHC. We evaluated the potential of TMEM14C as a prognostic biomarker using online databases such as TIMER, GEPIA2, UALCAN, OSlihc, and LinkedOmics. We observed that the mRNA expression of TMEM14C was upregulated in LIHC than that in normal tissues. Upregulated TMEM14C expression was associated with worse prognosis based on the clinicopathological characteristics of patients with LIHC. Furthermore, TMEM14C expression was positively associated with TIICs. In the co-expression and functional enrichment analyses of TMEM14C, 7,401 genes were positively associated with TMEM14C, whereas 12,520 genes showed negative associations. The results of gene set enrichment analysis (GSEA)-Gene Ontology showed that TMEM14C-related co-expression genes were involved in protein localization to translational elongation, protein localization to the endoplasmic reticulum, and mitochondrial gene expression. Furthermore, GSEA-Kyoto Encyclopedia of Genes and Genomes analysis showed that these genes regulated ribosomes, oxidative phosphorylation, and spliceosomes. A survival map revealed that 28 and 24 genes that were positively associated with TMEM14C showed significant hazard ratios for overall survival and diseasefree survival, respectively. Our findings demonstrate that TMEM14C is a novel prognostic biomarker and a potential tumor immune therapeutic target in patients with LIHC.