The optimal treatment for combined osteochondritis dissecans (OCD) with considerable bony defect of the lateral femoral condyle (LFC) and torn discoid lateral meniscus is unclear. We present a case of a 15-year-old female who was a gymnast and had a large OCD lesion in the LFC combined with deficiency of the lateral meniscus. The patient underwent the "one-step" technique of osteoperiosteal autologous iliac crest graft and lateral meniscus allograft transplantation after a failure of meniscectomy with repair at another hospital. Twenty-four months postoperatively, clinical results were significantly improved. Follow-up imaging tests and second-look arthroscopy showed well incorporated structured bone graft and fibrous cartilage regeneration as well as stabilized lateral meniscus allograft. She could return to her sport without any pain or swelling. This "one-step" surgical technique is worth considering as a joint salvage procedure for massive OCD lesions with torn discoid lateral meniscus.