Background: According to the anatomic characteristics of the calcaneus and the sinus tarsi approach, we designed a combined plate. The goal of this study was to retrospectively assess the functional outcomes and complications of treatment with our self-designed plate. Methods: From March 2014 to October 2015, 18 patients with closed calcaneal fractures (14 Sanders type II and 4 type III) were treated with our combined locking plate through a minimally invasive sinus tarsi approach. All patients underwent both clinical and radiological evaluations. Results: The follow-up duration for all patients ranged from 6 to 13.5 months. The radiographs demonstrated significant corrections of the calcaneal width, length, height, Böhler angle, and Gissane angle from preoperatively to 3 months postoperatively and the last follow-up. However, there were no significant differences in the variables between 3 months postoperatively and the last follow-up. The mean Maryland foot score was 88.1 ± 8.8, in which excellent outcomes were achieved in 11 patients, good in 4, and fair in 3 (excellent and good rate, 83.3% (15 of 18)). No statistical significances in the mean Maryland foot score (88.1 ± 8.8 vs 87.8 ± 10.1, p = 0.9), and the excellent and good rate (85.7 vs 75.0%, p = 1.0) was found between type II and type III fractures. No complications were observed in all fractured feet. Conclusion: Treatment with our self-designed combined plate through a sinus tarsi approach may be safe and effective for type II and type III calcaneal fractures.