Background Reduced estimated glomerular filtration rate (eGFR) and albuminuria have been associated with worse cognitive performance. However, few studies have examined whether these associations are confined to older individuals or may be extended to the middle-aged population. Study Design Cross-sectional analyses of a prospective population-based cohort study. Setting & Participants 2,987 individuals aged 40 to 75 years from the general population (The Maastricht Study). Predictor eGFR and urinary albumin excretion (UAE). Outcomes Memory function, information processing speed, and executive function. Measurements Analyses were adjusted for demographic variables (age, sex, and educational level), lifestyle factors (smoking behavior and alcohol consumption), depression, and cardiovascular disease risk factors (glucose metabolism status, waist circumference, total to high-density lipoprotein cholesterol ratio, triglyceride level, use of lipid-modifying medication, systolic blood pressure, use of antihypertensive medication, and prevalent cardiovascular disease). Results UAE was <15 mg/24 h in 2,439 (81.7%) participants, 15 to <30 mg/24 h in 309 (10.3%), and ≥30 mg/24 h in 239 (8.0%). In the entire study population, UAE ≥ 30 mg/24 h was associated with lower information processing speed as compared to UAE < 15 mg/24 h (β [SD difference] = −0.148; 95% CI, −0.263 to −0.033) after full adjustment, whereas continuous albuminuria was not. However, significant interaction terms (P for interaction < 0.05) suggested that albuminuria was most strongly and extensively associated with cognitive performance in older individuals. Mean (±SD) eGFR, estimated by the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine–cystatin C equation (eGFRcr-cys), was 88.4 ± 14.6 mL/min/1.73 m2. eGFRcr-cys was not associated with any of the domains of cognitive performance after full adjustment. However, significant interaction terms (P for interaction < 0.05) suggested that eGFRcr-cys was associated with cognitive performance in older individuals. Limitations Cross-sectional design, which limited causal inferences. Conclusions In the entire study population, albuminuria was independently associated with lower information processing speed, whereas eGFRcr-cys was not associated with cognitive performance. However, both were more strongly and extensively associated with cognitive performance in older individuals.