Abstract: Denosumab is a monoclonal antibody against the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) that significantly inhibits osteoclast activity and has been approved to treat osteoporosis, giant cell tumor of bone, and prophylactic as well as therapeutic entities for bone metastasis. However, the imbalance of RANKL/RANK/OPG has also been implicated in the pathogenesis of several other rare bone diseases and tumor-like disorders, including aneurysmal bone cyst, fibrous dysplasia of bone, and Langerhans cell histiocytosis. Nevertheless, there have been various clinical reports although these diseases have not been approved for indications. The review aims to summarize the available evidence for the off-label use of denosumab in metabolic bone diseases and tumor-like disorders and provide a reference for clinical diagnosis and treatment.