This narrative review summarizes current evidence on the role of aminothiols as biomarkers of oxidative stress in patients undergoing coronary artery bypass grafting (CABG). CABG is accompanied by profound oxidative and inflammatory stress driven by ischemia-reperfusion injury, cardiopulmonary bypass (CPB), and systemic immune activation. These processes disrupt redox homeostasis and contribute to myocardial injury, arrhythmogenesis, neurocognitive deficits, and impaired graft patency. Aminothiols, including glutathione, cysteine, homocysteine, and cysteinylglycine, are central regulators of intracellular and extracellular redox balance and have emerged as promising biomarkers in this setting. Evidence from clinical studies indicates that elevated preoperative homocysteine predicts perioperative complications, myocardial infarction, atrial fibrillation, and long-term mortality, while perioperative shifts in glutathione and thiol-disulfide ratios reflect oxidative stress dynamics induced by CPB. Interventional trials suggest that antioxidant therapies such as N-acetylcysteine, melatonin, and vitamin C may favorably modulate aminothiol metabolism, although findings remain inconsistent. Despite small sample sizes, methodological heterogeneity, and lack of standardized cut-offs, aminothiols offer mechanistic and prognostic insights. Their integration into multi-biomarker panels, supported by metabolomics and redox proteomics, could enhance perioperative risk stratification and guide personalized redox-modulating strategies in CABG. By synthesizing mechanistic and clinical data, this review highlights the potential of aminothiols for perioperative risk stratification and redox-modulating interventions.