Breast carcinoma is one of the leading causes of mortality among female cancers globally. Heparan sulfate proteoglycans, found predominantly on cell surfaces and in the extracellular matrix, are known to regulate breast cancer cellular behavior. Many studies have shown that these molecules serve as potential biomarkers for breast cancer. In addition, they have aberrant expression patterns and participate in various molecular signaling pathways in tumor progression. There is substantial interest in targeting heparan sulfate proteoglycans for cancer treatment, which needs to be tailored according to the roles that each proteoglycan plays in cancer biology. Current clinical trials using phosphomannopentaose sulfate, a heparan sulfate mimic, and various forms of heparin have produced promising results in breast cancer patients. Besides heparan sulfate chains, novel therapeutic agents could potentially be developed to regulate the proteoglycan core proteins as well as enzymes that modify heparan sulfation patterns. This review discusses the current use and future prospective applications of heparan sulfate proteoglycans, which have been recently patented, as therapeutic targets in breast cancer treatment.