Unicompartmental knee osteoarthritis (OA) is the early stage of knee joint degeneration, characterized by the degeneration of a single compartment of the knee, which occurs in the medial compartment mainly. The manifestations are knee pain and limited range of motion, which affect the quality of life of patients. Periarticular knee osteotomy is an effective treatment for unicompartmental knee OA with abnormal alignment of the lower extremity. By regulating the alignment of lower limbs, the pressure transferred from the diseased lateral compartment to the healthy lateral compartment or normal location, so as to relieve the keen pain and improve knee function. At present, there is no clinical guideline of periarticular knee osteotomy for alignment correction of the lower extremity in the treatment of unicompartmental knee OA. Through the experts discussion from the Chinese Hospital Association Clinical Medical Technology Application Committee, the Joint Surgery Branch of the Chinese Orthopaedic Association and the Subspecialty Group of Osteoarthritis, Chinese Association of Orthopaedic Surgeons, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used in this specific case to rate the quality of evidence and the strength of recommendations, and the Reporting Items for Practice Guidelines in Healthcare (RIGHT) checklist was strictly followed to report the guideline. Finally, 25 evidence-based recommendations were formulated based on 25 most concerned clinical problems among orthopaedic surgeons according to evidence retrieval, quality evaluation of body evidence, and establishment of direction and intensity of recommendations. Items 1-5 are indications and contraindications of periarticular knee osteotomy for lower extremity alignment correction; items 6-21 are surgical methods and principles of intraoperative management; item 22 is 3D printing osteotomy and orthopaedic technology; and items 23-25 are perioperative period and follow-up management. The purpose of this guideline is to improve the normalization and standardization of periarticular knee osteotomy for lower extremity alignment correction in knee OA.