To evaluate the oncologic outcomes among a large cohort of octogenarian patients placed on active surveillance for a localized renal mass. We retrospectively reviewed patients ≥80 years of age presenting for asymptomatic, incidentally detected clinically localized stage T1 renal mass between 2006 and 2013 who were followed by active surveillance (AS). The primary endpoint was development of metastatic renal cell carcinoma. Secondary outcomes included intervention-free survival, cancer-specific survival, and overall survival. Eighty-nine octogenarians (median age = 83.4 years) were placed on AS for a median 29.9 months. Median Charlson Comorbidity Index and Katz Index of Independence in Activities of Daily Living scores were 2 and 5, respectively. For all comers, median initial tumor size was 2.4 cm with median growth rate of 0.20 cm/year. Eight (9.0%) patients failed AS due to delayed intervention and three (1.1%) due to systemic progression after median follow-up of 27.8 and 39.9 months, respectively. Two (2.2%) patients in the delayed intervention cohort developed metastasis after treatment. Tumor growth rate was significantly higher among those undergoing intervention versus no intervention (0.60 vs. 0.15 cm/year, P = 0.05) and among patients with systemic progression versus no metastasis (1.28 vs. 0.18 cm/year, P = 0.001). Five-year intervention-free, metastasis-free, cancer-specific, and overall survivals were 90.6, 95.6, 95.6, and 85.7%, respectively. AS represents an effective management strategy in octogenarians given low overall risk of metastasis. Tumor growth kinetics may identify patients at risk of systemic progression in whom treatment should be considered.