Transforaminal endoscopic lumbar discectomy (TELD) is increasingly used as an effective alternative to open discectomy or microdiscectomy, supported by comparable outcomes in the literature. Advances in techniques and instrumentation now permit selective endoscopic decompression of diverse disc pathologies, including complex stenosis cases. However, the rising number of procedures has been accompanied by a corresponding increase in complications, which has been exacerbated by heterogeneous reporting standards in literature. Standardized systems for defining, classifying, and scoring TELD complications are lacking, but would be essential for quality assurance, comparative studies, research, and outcome assessment. Therefore, we systematically reviewed the literature to identify studies focusing on TELD complications and propose a consensus classification system. PubMed, Scopus, and Science Direct were searched to identify studies primarily addressing complications, or their classification, in patients with lumbar disc herniation or lumbar canal stenosis undergoing TELD. The exclusion criteria encompassed studies involving other pathologies, such as infections or tumors, and studies with patients undergoing revision surgery. Initial database searches yielded 887 articles, with 560 unique articles after duplicate removal. Title and abstract screening excluded 313 articles, leaving 247 articles for full-text assessment. Ultimately, 95 articles met the inclusion criteria. The narrative synthesis focused on compiling complications associated with TELD, which helped propose a structured classification system. Complications in TELD can match or exceed those of traditional surgical procedures, influenced by a steep learning curve and longer initial operation times. Expanded indications introduce the potential for encountering previously unreported complications even among experienced surgeons. Effective documentation, rating, and follow-up of complications are crucial for informed treatment decisions, enhancing patient consent processes, and improving overall outcomes.