Selective upper airway stimulation (UAS) is a novel therapy for patients with obstructive sleep apnea (OSA). The aim of this study was to analyze the application and outcome of UAS in patients with moderate to severe OSA in the clinical routine of a tertiary referral center. The design of this study is single-center, prospective clinical trial. Thirty-one patients who received a UAS device (Inspire Medical Systems) were included. Treatment outcome was evaluated at 2, 3, 6, and 12 months after surgery. Data collection included demographics, body mass index (BMI), apnea hypopnea index (AHI), oxygen saturation and desaturation index (ODI), Epworth Sleepiness Score (ESS), adverse events, and adherence to therapy. Sher criteria were used to evaluate treatment response. The mean age was 59.6 years with thirty patients being male. Mean BMI was 28.8 kg/m(2). The mean pre-implantation AHI of 32.9/h could be reduced to 7.1/h after 12 months (p < 0.001). The mean pre-implantation ODI of 30.7/h could be reduced to 9.9/h after 12 months (p = 0.004). The mean pre-implantation ESS of 12.6 could be reduced to 5.9 after 12 months (p = 0.006). Serious adverse events did not occur. Therapy adherence was a usage of 6.6 h/night after 12 months. OSA severity and subjective daytime sleepiness were improved in patients with moderate to severe OSA after receiving UAS therapy. Patients maintained high adherence to therapy use after 12 months. It is encouraging that UAS has been shown to be successfully implemented in the routine clinical management of OSA outside of a clinical trial setting.