Umbilical cord blood mesenchymal stem cells (UCB-MSCs) are a type of adult stem cell with multipotent differentiation potential and immunoregulatory functions, primarily found in neonatal cord blood. Due to their noninvasive collection method, abundance, and ease of preservation, UCB-MSCs represent a promising biological material. This review examines the clinical research on UCB-MSCs in knee articular cartilage repair, highlighting their regenerative potential for treating knee joint cartilage defects. Our aim is to provide insights into current applications and propose directions for future research, focusing on optimizing clinical use and enhancing patient outcomes.