Introduction: Knowing an individualized outcome prediction is essential when counseling patients before surgery. We aim to identify predictors and build a model for the outcome of radiofrequency uvulopalatopharyngoplasty with tonsillectomy (rfUPPP + TE). Methods: All adult patients undergoing rfUPPP + TE for sleep-disordered breathing from 2015 to 2022 in our institution were included. Preoperative evaluations included detailed upper airway examinations and standardized questionnaires. Postoperative outcomes were measured through home sleep apnea testing and repeated questionnaires 3 months post-surgery. The primary endpoint was the postoperative apnea-hypopnea index (AHI) and the AHI responders using the Sher criteria. Results: We analyzed 247 patients with a mean age of 46 ± 11 years, predominantly male (88.7%), and a mean BMI of 29.0 kg/m2. The mean AHI was reduced from 26.4 ± 18.6/h preoperatively to 16.2 ± 14.6/h postoperatively. Daytime sleepiness improved from 8.9 ± 48 to 4.0 ± 3.1 and snoring from 7.9 ± 2.1 to 3.3 ± 2.2. Multivariate analysis indicated that higher tonsil grades, preoperative AHI, and snoring levels were associated with a greater reduction in AHI. Age and body weight were negative predictors for AHI reduction. For AHI responders, according to Sher, tonsil grade was the only predictor in a multivariate analysis. The ROC curve of this simple model, with a corrected AUC of 0.625, compared favorably against two established models. Conclusion: Our study highlights that tonsil grade, preoperative AHI, snoring, and, to a smaller extent, age and weight are key determinants of AHI reduction, emphasizing the importance of preoperative evaluation. Despite the multifactorial nature of obstructive sleep apnea, preoperative evaluation can predict the outcome of rfUPPP + TE and guide surgical planning.