The role of protein arginine methyltransferases (PRMTs) in benign and malignant liver diseases has garnered considerable attention. PRMTs play a key function in regulating protein methylation modification in diseases such as alcoholic fatty liver disease, metabolic dysfunction–associated steatotic liver disease, viral hepatitis, and hepatocellular carcinoma. This review explores the mechanisms of action of PRMTs in these diseases, with a focus on their effects on cell signaling, transcriptional regulation, cell proliferation, and metabolism. We also discuss potential therapeutic strategies targeting PRMTs and propose future research directions. This review helps deepen the understanding of the important role of arginine methylation modification in the malignant progression of liver diseases and provides guidance for future clinical treatment and drug development.