Background Chronic kidney disease is associated with an increased risk of cancer, but whether reduced kidney function also leads to increased cancer mortality is uncertain. The aim of our study was to assess the independent effects of reduced kidney function on the risk of cancer deaths. Study Design Prospective population-based cohort study. Setting & Participants Participants of the Blue Mountains Eye Study (n = 4,077; aged 49-97 years). Predictor Estimated glomerular filtration rate (eGFR). Outcomes Overall and site-specific cancer mortality. Results During a median follow-up of 12.8 (IQR, 8.6-15.8) years, 370 cancer deaths were observed in our study cohort. For every 10-mL/min/1.73 m2 reduction in eGFR, there was an increase in cancer-specific mortality of 18% in the fully adjusted model (P < 0.001). Compared with participants with eGFR ≥ 60 mL/min/1.73 m2, the adjusted HR for cancer-specific mortality for those with eGFR < 60 mL/min/1.73 m2 was 1.27 (95% CI, 1.00-1.60; P = 0.05). This excess cancer mortality varied with site, with the greatest risk for breast and urinary tract cancer deaths (adjusted HRs of 1.99 [95% CI, 1.05-3.85; P = 0.01] and 2.54 [95% CI, 1.02-6.44; P = 0.04], respectively). Limitations Residual confounding, such as from unmeasured socioeconomic factors and the potential effects of erythropoiesis-stimulating agents on cancer deaths, may have occurred. Conclusions eGFR < 60 mL/min/1.73 m2 appears to be a significant risk factor for death from cancer. These effects appear to be site specific, with breast and urinary tract cancers incurring the greatest risk of death among those with reduced kidney function.