Advanced liver disease, including cirrhosis and hepatocellular carcinoma (HCC), represents a major global health challenge, particularly due to the increasing prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD). Simultaneously, micronanoplastics (MNPs) have emerged as pervasive environmental contaminants with potential hepatotoxic effects. In this review, our aims were to provide an in-depth analysis of the current knowledge on the role of MNPs in the pathogenesis of cirrhosis and HCC, particularly in the context of the increasing prevalence of MASLD, and to identify key areas for future research. The search strategy encompassed original studies and review articles included in PubMed/MEDLINE, Web of Science, Scopus, and Google Scholar databases from January 1, 2014, to November 1, 2024. Growing evidence indicates that MNPs exposure in animal models may induce hepatic changes similar to those observed in human MASLD and metabolic dysfunction-associated steatohepatitis through both direct and indirect mechanisms. Importantly, MNPs may function as a “second hit” in the presence of pre-existing metabolic stress, potentially exacerbating hepatotoxic damage. However, data from human studies remain limited, with only two small-scale investigations examining MNPs in clinical cohorts. Recent advancements in analytical methods for quantifying MNPs in blood present new opportunities to investigate their association with the risk of MASLD, cirrhosis, and HCC in clinical cohorts. In conclusion, while significant progress has been made in elucidating the hepatotoxic effects of MNPs in experimental models, their clinical relevance to human liver disease progression remains largely unexplored. Further multidisciplinary research integrating environmental science, molecular biology, and clinical hepatology is urgently needed.