Proteoglycans are essential components of the cartilage extracellular matrix (ECM), with glycosaminoglycan (GAG) chains playing a crucial role in skeletal development. This study identifies a previously unknown substrate of arylsulfatase L (ARSL) a Golgi-localized enzyme. To investigate ARSL’s physiological substrate, the study utilized the TurboID proximity labeling approach. TurboID, a biotin ligase, biotinylates interacting proteins, allowing their isolation via streptavidin beads and identification through mass spectrometry (MS). We generated RCS (Rat chondrosarcoma) cells overexpressing FLAG-TurboID-Arsl, confirming its Golgi localization. MS analysis revealed 129 significantly enriched proteins in ARSL-labeled samples, with gene ontology (GO) analysis highlighting extracellular matrix organization. Among these proteins, Acan, a precursor of Aggrecan—rich in sulfated GAGs—was identified as a key ARSL interactor, reinforcing the enzyme’s role in ECM regulation and skeletal development.