Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality globally, characterized by high incidence and complex molecular heterogeneity [1, 4]. Despite advances in early diagnosis and treatment, prognostic biomarkers and effective therapeutic targets remain crucial for improving patient outcomes [2, 3, 4]. The minichromosome maintenance (MCM) protein family plays a pivotal role in DNA replication, acting as integral components of the pre-replication complex [9]. This study investigates the prognostic significance of Minichromosome Maintenance Protein 3 (MCM3) in HCC and its correlation with key biological processes, including cell proliferation, cell cycle regulation, and immune modulation within the tumor microenvironment. Our comprehensive analysis, integrating bioinformatics and experimental validation, reveals that overexpression of MCM3 is a significant independent prognostic biomarker for poor overall survival in HCC patients. Furthermore, high MCM3 levels are strongly associated with increased cell proliferation, dysregulated cell cycle progression, and alterations in the immune landscape, suggesting its crucial role in HCC malignancy. These findings highlight MCM3 as a promising prognostic marker and a potential therapeutic target for HCC.