Although heart transplantation remains the gold standard for management of heart failure, ventricular assist devices (VAD) have emerged as viable alternatives. VAD implantation improves kidney function. However, whether the improvement is sustained or associated with improved outcomes is unclear. Herein we assess kidney function improvement, predictors of improvement, and associations with thromboembolism, hemorrhage, and mortality in VAD patients. Kidney function was defined using chronic kidney disease (CKD) stages: stage 1 (glomerular filtration rate [eGFR] ≥ 90 ml/min/1.73 m2), stage 2 (eGFR 60–90 ml/min/1.73 m2), stage 3a (eGFR 45–59 ml/min/1.73 m2), stage 3b (eGFR 30–44 ml/min/1.73 m2), stage 4 (eGFR 15–30 ml/min/1.73 m2), and stage 5 (eGFR < 15 ml/min/1.73 m2). Improvement in kidney function was defined as an improvement in eGFR that resulted in a CKD stage change to one of lesser severity. Kidney function improved post implant, and was maintained over 1 year for all patients, except those with baseline stage 5 CKD. Younger age at implantation (OR 0.93, 95% CI: 0.90–0.96, P < 0.0001) was associated with sustained improvement in kidney function. Poor kidney function was associated increased mortality but not with thromboembolism or hemorrhage. Compared to patients with baseline eGFR > 45 ml/min/1.73 m2; patients with eGFR < 45 ml/min/1.73 m2 had a higher mortality risk (HR 3.32, 95% CI: 1.10–9.98, p = 0.03 for stage 3b; HR 4.07, 95% CI: 1.27–13.1, p = 0.02 for stage 4; and HR 4.01, 95% CI: 1.17–13.7, p = 0.03 for stage 5 CKD). Kidney function was not associated with thromboembolism or hemorrhage, and sustained improvement was not associated with lower risk of death. However, poor kidney function at implantation was associated with an increased risk of mortality.