Patients with end-stage heart failure frequently experience renal impairment due to cardiorenal syndrome (CRS), often without known true baseline kidney function. Clinical prediction of renal recovery in those patients following left ventricular assist device (LVAD) remains challenging. We aimed to identify predictors of post-LVAD renal recovery in patients with pre-existing renal impairment. We analyzed patients with impaired kidney function (creatinine-based eGFR <60mL/min/1.73m2) or under renal replacement therapy (RRT) who underwent HeartMate 3 LVAD implantation at a tertiary hospital in Korea between 2020 and 2024. Patients were classified into recovery and non-recovery groups. Renal recovery was defined as a ≥50% increase in eGFR or liberation of RRT. Predictive factors were assessed using a logistic regression model. Among 113 patients who underwent LVAD, 77 patients had pre-existing kidney dysfunction, including 34 patients on RRT and 43 patients with reduced eGFR (<60 mL/min/1.73m2). The median age was 64.0 (54.0–71.0), and the cohort was predominantly male (83.1%). Renal recovery rates after LVAD implantation were 64.9%, 77.9%, 81.8%, and 81.8% at 1, 2, 3, and 6 months, respectively. Notably, in patients whose renal function did not recover within 3 months, no further renal recovery was observed thereafter. After adjusting multiple covariates, predictive factors for renal recovery at 1 month were younger age (OR 0.74/year increase, 95%CI 0.59–0.92), use of renin-angiotensin system (RAS) blockers (23.81, 2.02–607.88), and absence of proteinuria (0.02, 0.01–0.21), and presence of tricuspid regurgitation (29.69, 3.01–626.73) before surgery. At 2 and 3 months after LVAD implantation, preoperative RAS blocker use and presence of tricuspid regurgitation remained independent predictors of renal recovery. In patients with pre-existing kidney dysfunction, withholding RAS blockade, a part of guideline-directed medical therapy, may negatively impact renal recovery following LVAD implantation. Additionally, pre-LVAD tricuspid regurgitation may serve as a contributing factor or a marker of reversible CRS in this population.