Protein arginine methyltransferases (PRMTs) catalyze arginine methylation, an essential protein posttranslational modification involved in a variety of biological processes, such as transcription, RNA splicing and the DNA damage response (DDR), protein stability, and signal transduction. Due to their significant roles in these processes, PRMTs have emerged as promising therapeutic targets in cancer. Among all cancer types, breast cancer has been the most extensively studied in relation to PRMTs dysregulation. Previous studies have reported that several PRMTs are overexpressed in breast cancer and play critical roles in tumor growth, metastasis, and the maintenance of breast cancer stem cells. Moreover, an increasing number of PRMT inhibitors are undergoing clinical trials for breast cancer treatment, demonstrating significant progress. This review aims to provide a comprehensive overview of the biological functions of PRMTs in breast cancer and to summarize the latest clinical developments of PRMT inhibitors for cancer therapy.