<b><i>Background:</i></b> Chronic kidney disease (CKD) affects more than one third of older adults, and is a strong risk factor for vascular disease and cognitive impairment. Cognitive impairment can have detrimental effects on the quality of life through decreased treatment adherence and poor nutrition and results in increased costs of care and early mortality. Though widely studied in hemodialysis populations, little is known about cognitive impairment in patients with pre-dialysis CKD. <b><i>Methods:</i></b> Multicenter, cross-sectional, prospective cohort study including 385 patients with CKD stages G4-G5. Cognitive function was measured with a validated tool called the Montreal Cognitive Assessment (MoCA) as part of a comprehensive frailty assessment in the Canadian Frailty Observation and Interventions Trial. Cognitive impairment was defined as a MoCA score of ≤24. We determined the prevalence and risk factors for cognitive impairment in patients with CKD stages G4-G5, not on dialysis. <b><i>Results:</i></b> Two hundred and thirty seven participants (61%) with CKD stages G4-G5 had cognitive impairment at baseline assessment. When compared to a control group, this population scored lower in all domains of cognition, with the most pronounced deficits observed in recall, attention, and visual/executive function (p < 0.01 for all comparisons). Older age, recent history of falls and history of stroke were independently associated with cognitive impairment. <b><i>Conclusions:</i></b> Our study uncovered a high rate of unrecognized cognitive impairment in an advanced CKD population. This impairment is global, affecting all aspects of cognition and is likely vascular in nature. The longitudinal trajectory of cognitive function and its effect on dialysis decision-making and outcomes deserves further study.