To evaluate the safety and efficacy, and long-term functional and oncologic outcomes of robot-assisted partial nephrectomy in high-complexity tumors. Methods: Data of 155 patients with a high-complexity tumor (PADUA score ≥10) were reviewed. Trifecta achievement, intra-, perioperative, functional, and oncologic outcomes were analyzed and compared between patients with increasing complexity. Results: Of the 155 patients, 65 (41.9%) patients had a PADUA score of 10, 55 (35.5%) had a PADUA score of 11, and 35 (22.6%) had a PADUA score of 12-13, respectively. The median (interquartile range) operative time, warm ischemia time and estimated blood loss were 150 min (112-186 min), 26 min (23-32 min) and 250 mL (100-500 mL), respectively. Postoperatively, complications occurred in 25 (16.1%) patients, and positive surgical margins in 15 (10.5%) patients. Trifecta was achieved in 67 (43.2%) patients. At a median follow-up period of 58 months, the median estimated glomerular filtration rate preservation was 87% (78-110), and 12 (7.7%) patients developed new-onset chronic kidney disease. Recurrence-free survival and overall survival rates were 93.6% and 96.7%, respectively. Positive surgical margins were statistically different between the groups of PADUA score 10, 11 and 12-13 (P = 0.017), whereas functional and oncologic outcomes were similar. In multivariate logistic regression analysis, increasing tumor size (odds ratio 1.48, 95% confidence interval 1.21-1.87; P < 0.001) and the American Society of Anesthesiologists score 2/3 (odds ratio 0.48, 95% confidence interval 0.24-0.96; P = 0.041) were independent predictors of trifecta failure. Conclusions: Robot-assisted partial nephrectomy is a safe and effective treatment for high-complexity tumors providing excellent long-term functional and oncologic outcomes.