Myocardial injury is a major predictor of adverse cardiovascular outcomes and is driven by both ischemic and inflammatory mechanisms. Hyperbaric oxygen therapy (HBOT), which delivers 100% oxygen at supra-atmospheric pressure, has been proposed to enhance tissue oxygenation, attenuate ischemia-reperfusion injury, and modulate inflammatory responses. However, its clinical effects on myocardial injury and inflammatory biomarkers remain unclear. This systematic review qualitatively synthesizes clinical evidence evaluating the impact of HBOT on myocardial injury and inflammatory biomarkers in adult patients. A systematic search of PubMed, Web of Science, Scopus, and the Cochrane Library through May 2025 identified randomized controlled trials and observational studies reporting myocardial injury markers (cardiac troponin I, cardiac troponin T, creatine kinase-myocardial band, creatine phosphokinase (CPK)) or inflammatory/endothelial biomarkers (C-reactive protein, high-sensitivity CRP, interleukin-6, tumor necrosis factor-alpha, endothelin-1, nitric oxide, adhesion molecules, heat shock protein 70). A meta-analysis was not performed due to substantial heterogeneity and incomplete reporting of dispersion measures. Five clinical studies including 431 patients were eligible. In acute myocardial infarction, HBOT was associated with reduced CPK levels (up to 35% reduction, p=0.03) and improved left ventricular ejection fraction (p<0.05) in randomized studies. In perioperative cardiac surgery settings, HBOT preconditioning was associated with lower postoperative inflammatory and myocardial injury biomarkers (p<0.05). In patients with chronic coronary artery disease, HBOT was linked to reductions in high-sensitivity CRP and endothelin-1 and increased nitric oxide levels (p<0.05), although one multicenter trial reported a non-significant reduction in CPK. Overall, current evidence suggests that HBOT may exert cardioprotective and anti-inflammatory effects through improved oxygen delivery and modulation of inflammatory pathways. However, available studies remain limited and heterogeneous, and larger, well-designed prospective trials are required to establish clinical benefit.