Background Management of upper gastrointestinal leaks is challenging. A new potential treatment option for this complication is endoscopic suturing with the OverStitch system (Apollo Endosurgery, Texas, USA), which is today mainly used for endoscopic sleeve gastroplasty. The aim of this study was to analyze the efficacy and feasibility of this new treatment option in patients with leaks in the upper gastrointestinal tract. Methods We performed a retrospective, single-center study of all patients who underwent endoscopic suturing with OverStitch of leaks in the upper gastrointestinal tract. Results Endoscopic suturing was performed on 13 patients (mean age, 59.62 ± 16.29 years; mean leak size, 22.31 ± 22.6 mm) over a period of 8 months. Postoperative leaks were detected in 10 patients (76.9%) after foregut surgery. Interventional success was achieved in all endoscopic attempts ( n  = 16, 100%) with a mean closure time of 28.0 ± 12.36 min per patient. Follow-up technical success rate for each suture was ( n  = 8, 50.0%). Clinical success, including repeated suture attempts was achieved in 8 of the 13 patients (61.5%). These 8 patients had not received prior treatment for the leak. No immediate or delayed serious complications occurred as a result of OverStitch. The mean follow-up was 95 ± 91.07 days. Conclusions Endoscopic suturing with OverStitch for leaks in the upper gastrointestinal tract is feasible and effective in patients who have not received prior treatment. This minimally invasive technique seems to be a promising option especially for patients with large leaks and significant comorbidities.