Objective: To compare and analyze surgical and functional outcomes of transperitoneal robotic partial nephrectomy (TRPN) and retroperitoneal robotic partial nephrectomy (RRPN) in localized renal tumors, including ‡4 cm renal masses. Methods: Of 566 consecutive patients who underwent robotic partial nephrectomy by a single surgeon from December 2008 through July 2017, records for 523 patients who were preoperatively and 1 year postoperatively evaluated were analyzed for estimated glomerular filtration rate (eGFR). Primary endpoint was a comparison of Pentafecta criteria (negative surgical margin, no 30-day complications, warm ischemic time [WIT] £25 minutes, return of eGFR to >90% from baseline, and no upstaging of chronic kidney disease) between TRPN and RRPN. Secondary endpoint was finding predictors for Pentafecta achievement. Results: In all 523 patients, these Pentafecta criteria were lower for RRPN than TRPN: operation time ( p < 0.001), WIT ( p = 0.008), and estimated blood loss ( p = 0.003). In patients with ‡4 cm renal tumors, only operation time was faster in RRPN than TRPN ( p = 0.032). RRPN demonstrated more eGFR decrease in all patients ( p = 0.006) and patients with ‡4 cm renal tumors ( p = 0.008). Pentafecta achievements, complications, and recurrences were not significantly different between TRPN and RRPN in all patients and patients with ‡4 cm renal tumors. Multivariable analysis revealed baseline hemoglobin ( p = 0.013) and tumor size ( p < 0.001) were predictive for Pentafecta achievement. Conclusions: Pentafecta achievement was similar for TRPN and RRPN. Baseline hemoglobin and tumor size were predictors of Pentafecta achievement. RRPN was properly performed for anterolateral renal tumor.