Background: The lactate dehydrogenase to albumin ratio (LAR) is a novel inflammatory marker and a potential predictor of mortality in various conditions. No research has yet examined LAR’s impact on mortality in cardiac surgery patients. This study evaluated LAR’s role in predicting mortality and complications in isolated coronary artery bypass grafting (CABG) patients. Methods: A retrospective analysis of 377 CABG patients (93 women, 24.7%; 284 men, 75.3%; mean age 65.9 years) from 2020 to 2024 was conducted. Data included demographics, preoperative characteristics, surgical details, and postoperative outcomes, along with ICU and hospital length of stay (LOS). Results: In-hospital mortality was 6.1% (n = 23). Independent predictors were low preoperative ejection fraction (EF) (OR: 0.96, p = 0.024), baseline LAR (OR: 1.08, p = 0.000), LOS-ICU (OR: 1.1, p = 0.000), postoperative ventricular tachycardia (OR: 37.9, p = 0.006), and acute renal failure (OR: 12.1, p = 0.000). Mortality cases had a higher median LAR than survivors (8.6 vs. 5.2, p = 0.000). Elevated LAR correlated with lower preoperative EF (r = −0.227, p = 0.000), longer LOS-ICU (r = 0.17, p = 0.001), and longer LOS-hospital (r = 0.208, p = 0.000). A LAR cut-off of 7.097 predicted mortality (AUC: 0.823, sensitivity 78.3%, specificity 77.1%). Elevated LAR values were observed in all groups with postoperative complications (p < 0.05), indicating its consistent association with negative outcomes. Conclusions: LAR is a valuable predictor of in-hospital mortality and postoperative complications in CABG patients. Elevated LAR is associated with longer ICU/hospital stays and poorer outcomes. Preoperative LAR assessment can guide risk stratification, forecast mortality, and inform surgical planning and treatment strategies.