Decorin (DCN) antibodies are immunological tools designed to target decorin, a small leucine-rich proteoglycan (SLRP) abundant in the extracellular matrix (ECM). Decorin plays multifaceted roles in tissue homeostasis, primarily through interactions with collagen fibrils to regulate their assembly and organization. It also modulates cell signaling by binding to growth factors (e.g., TGF-β) and receptors (e.g., EGFR), influencing cell proliferation, migration, and apoptosis. Dysregulation of decorin is implicated in pathological conditions, including fibrosis, cancer, and inflammatory diseases. In cancer, decorin acts as a tumor suppressor by inhibiting angiogenesis and metastasis, making DCN antibodies valuable for studying tumor-microenvironment crosstalk. In fibrotic disorders, decorin’s ECM-remodeling properties are of therapeutic interest. DCN antibodies are widely used in research to detect decorin expression via techniques like Western blot, immunohistochemistry, and immunofluorescence. They also hold potential as diagnostic or therapeutic agents, particularly in targeting decorin’s anti-oncogenic or anti-fibrotic pathways. Recent studies explore engineered decorin-based biologics, further driving demand for high-specificity DCN antibodies. Understanding decorin’s dual role in ECM structure and cellular signaling continues to expand its relevance in biomedicine.