Background and Aims Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer, with insidious onset and poor prognosis, and ranks the third leading cause of cancer-related deaths worldwide. KIF4A is highly expressed in a variety of malignancies and strongly associated with poor prognosis. However, the role and mechanism underlying KIF4A in HCC remain unclear. Therefore, this study was conducted to investigate the expression and prognostic value of KIF4A in HCC, and the associated mechanism.Methods The expression data and clinical parameters associated with HCC were obtained from the Cancer Genome Atlas (TCGA) and the expression levels of KIF4A in HCC and its relationship with clinicopathologic features were analyzed using software such as R language and Perl package. The prognostic value of KIF4A in HCC was evaluated by the Kaplan-Meier survival analysis and time-dependent ROC curves. The independent risk factors for the prognosis of HCC patients were determined by univariate and multivariate Cox regression analysis. A nomogram for predicting the prognosis of HCC patients was constructed by including relevant clinicopathologic factors using R software. Immunohistochemical staining was performed to verify the expression levels of KIF4A in the clinical specimens of HCC tissues and their adjacent noncancerous tissues. The molecular signaling pathways potentially regulated by KIF4A in HCC were analyzed by GSEA enrichment analysis.Results The expression level of KIF4A in HCC tissues was significantly higher than that in normal liver tissues (P<0.001). The overall survival (OS) time of patients with high KIF4A expression was shorter than that of those with low KIF4A expression (P=0.002), and the area under curve (AUC) of ROC curves for the 1-, 3-, and 5-year OS were 0.783, 0.662 and 0.574, respectively. The clinical stage (HR=2.084, 95% CI=1.590-2.733，P<0.001), T stage (HR=1.980, 95% CI=1.541-2.543，P<0.001) and KIF4A expression level (HR=1.113, 95% CI=1.062-1.167，P<0.001) were significantly associated with OS, and high expression of KIF4A (HR=1.089, 95% CI=1.034-1.147， P=0.001) was an independent risk factor for the prognosis of HCC patients. The nomogram results showed that KIF4A expression had a significant effect on the total score, while other clinicopathologic factors had relatively little effect on the total score. Immunohistochemical detection confirmed that KIF4A was positively expressed in HCC tissues, whereas it was weakly positively or negatively expressed in adjacent liver tissues. The results of GSEA enrichment analysis suggested that KIF4A was possibly involved in the regulation of nine signaling pathways that included base excision repair, cell cycle, DNA replication, mismatch repair, mTOR signaling pathway, nucleotide excision repair, P53 signaling pathway, pathways in cancer, and phosphatidylinositol signaling system.Conclusion KIF4A is highly expressed in HCC tissue and significantly correlated with the clinical stage and histological grade as well as poor prognosis of HCC patients, suggesting that KIF4A may be a potential molecular marker for prognostic prediction and targeted therapy for HCC patients.