Objective To investigate the effectiveness of basal osteotomy of the first metatarsal combined with first metatarsophalangeal joint replacement for the treatment of hallux valgus combined with hallux rigidus. Methods A retrospective analysis was conducted on the medical records of 15 patients (16 feet) with hallux valgus combined with hallux rigidus who underwent first metatarsal osteotomy combined with first metatarsophalangeal joint replacement between May 2019 and December 2024. The patients included 1 male and 14 females, aged 60-80 years, with an average age of 68.5 years. According to the Mann classification of hallux valgus, 2 feet were moderate and 14 feet were severe. According to the Hallux Rigidus Coughlin grading, 12 feet were grade 3 and 3 feet were grade 4. The evaluation indicators included hallux valgus angle (HVA) and 1-2 inter metatarsal angle (1-2 IMA) measured on weight-bearing X-ray film at preoperation and last follow-up; the American Orthopaedic Foot and Ankle Society (AOFAS) score and visual analogue scale (VAS) score were used to evaluate the improvement of walking function, metatarsophalangeal joint function, and pain relief in patients. Results All patients underwent surgery successfully without complications such as vascular or nerve injury during operation. One foot developed a superficial incisional infection postoperatively, which healed after dressing changes; the remaining 15 feet had primary incision healing. All patients were followed up 5-55 months, with an average of 17.5 months. All osteotomies achieved bony union, with a union time ranging from 8 to 13 weeks, averaging 11.8 weeks; no elevation of the first metatarsal was observed. At last follow-up, no complications such as prosthesis loosening, dislocation, fracture, toe shortening, bone dissolution, synovial reaction, or metatarsalgia were found. The appearance and function of the affected feet significantly improved, and the pain significantly relieved. At last follow-up, the HVA, 1-2 IMA, AOFAS score, and VAS score showed significant differences when compared with preoperative values (P<0.05). Conclusion Basal osteotomy of the first metatarsal combined with first metatarsophalangeal joint replacement for the treatment of hallux valgus with hallux rigidus can correct deformities through osteotomy, restore the normal flexion-extension axis of the metatarsophalangeal joint, relieve pain, and preserve a certain degree of mobility, achieving good medium-term effectiveness.