Objective To evaluate the early effectiveness of a new minimally invasive plate in the treatment of varus-type ankle arthritis. Methods A clinical data of 15 patients with varus-type ankle arthritis who met the selection criteria between March 2021 and October 2021 were retrospectively analyzed. All the patients were treated with medial open-wedge supramalleolar osteotomy and fibular osteotomy. The osteotomies were fixed with the new minimally invasive plate. There were 7 males and 8 females with an average age of 49.8 years (range, 16-71 years). The causes of ankle arthritis included post-fracture deformity in 1 case, sprain in 8 cases, and acquired clubfoot in 1 case; and 5 cases were without obvious factors. The disease duration ranged from 1 to 12 years, with an average of 4.1 years. Comparisons were made between pre-operation and the last follow-up in the Takakura staging, the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, foot function index (FFI), visual analogue scale (VAS) score, tibial anterior surface angle (TAS), tibial lateral surface angle (TLS), and talar tilt (TT). Results All incisions healed by first intention. All patients were followed up 7-18 months (mean, 12.8 months). At last follow-up, the AOFAS ankle-hindfoot score, FFI, VAS score, and Takakura staging significantly improved when compared with the preoperative ones (P<0.05). X-ray films showed that the osteotomy healed at 3 months after operation. At last follow-up, TAS significantly increased and TT decreased when compared with the preoperative ones (P<0.05), and the difference in TLS between pre- and post-operation was not significant (P>0.05). Complications included 1 case of intraoperative screw breakage and 2 cases of nerve injury of the affected foot. None of the patients complained of significant discomfort at the plate placement during follow-up, and no loosening of the internal fixator occurred. Eleven patients were very satisfied with the effeectiveness, while 4 were relatively satisfied. Conclusion The new minimally invasive plate for the varus-type ankle arthritis has good early effectiveness in relieving ankle pain, correcting deformity, improving limb alignment and ankle function, and reducing the incidence of postoperative incisional complications.