Renal function after partial nephrectomy (PN) may depend on modifiable factors including ischemia time, excision of healthy parenchyma (excisional volume loss, EVL), and reconstructive methods. We retrospectively reviewed our institutional robotic PN database to identify the predictors of glomerular filtration rate (GFR) preservation (GFR-P) at 3-12 mo postoperatively, during which GFR decline plateaus. Baseline clinical, sociodemographic, and radiologic characteristics were captured. Univariate and multivariate (MV) linear regression analyses were performed and marginal effects were employed to examine the relative effect of EVL on renal function. A total of 647 patients who underwent robotic PN had GFR data at a median follow-up of 6 mo. On MV models, EVL was significantly correlated with GFR-P following log transformation (p=0.001). Each doubling of EVL caused a 1.5% decrease in GFR-P. Ischemia time and tumor complexity were not significantly associated with GFR-P. In summary, GFR-P after PN appears to be significantly associated with the excised volume of benign parenchyma. At a high-volume tertiary care center, we investigated the impact of surgical factors on kidney function after kidney cancer surgery. We found that the surgical precision with which the tumor is excised significantly impacts kidney function at 3-12 mo after surgery.