Gout is an inflammatory disease commonly characterized by tophus deposits containing uric acid crystals in the intraarticular joints. An acute locked joint due to gouty tophus formation is a rare finding. This case describes a 36-year-old man with sudden pain and locking in the knee joint. Physical examination, plain radiography, and serum uric acid examination showed unremarkable results. Further investigation with diagnostic arthroscopy confirmed tophaceous gout as the sole cause of an acutely locked knee. The patient exhibited satisfactory clinical results following surgical intervention under arthroscopy and the administration of urate-lowering agents. This case highlights the probability of tophus deposition as the cause of an acute locked knee, despite unremarkable initial presentation. The awareness regarding this case should be raised, especially on emphasizing arthroscopy as a cost-effective diagnostic and therapeutic modality in patient management.