Introduction: Red cell distribution width (RDW), routinely reported in the complete blood count, reflects erythrocyte size variability. Although traditionally used in anemia evaluation, elevated RDW has been increasingly linked to cardiovascular morbidity, heart failure, and mortality. Proposed mechanisms include chronic inflammation, oxidative stress, impaired erythropoiesis, and reduced red cell deformability. Acute coronary syndrome (ACS) without ST-segment elevation—comprising unstable angina (UA) and non–ST-elevation myocardial infarction (NSTEMI)—is a major cause of cardiovascular disease, making early risk assessment essential. RDW has emerged as a simple and widely accessible prognostic marker in ACS. This study assesses the prognostic significance of RDW in UA and NSTEMI. Methodology: A hospital-based cross-sectional study was conducted over 18 months among adults diagnosed with UA or NSTEMI. Patients with anemia, chronic kidney disease, malignancy, hemoglobinopathies, COPD, pregnancy, recent transfusion, or STEMI were excluded. RDW and clinical parameters were recorded at admission, and patients were categorized into increased (>14%) and normal RDW groups. All participants were monitored for major adverse cardiac events (MACE), including heart failure, arrhythmias, cardiogenic shock, and in-hospital mortality. Chi-square tests were applied, with significance set at p <0.05. Results: Of the 260 patients enrolled, 58.1% had elevated RDW. MACE occurred in 20.4% of the study population, with significantly higher prevalence among those with increased RDW (71.7% vs. 28.3%, p = 0.024). Elevated RDW was strongly associated with diabetes (p <0.001) and showed borderline significance with hypertension (p = 0.05). Conclusion: RDW is an inexpensive and effective prognostic indicator in UA/NSTEMI, showing significant associations with adverse outcomes and cardiovascular risk factors. Its routine use may improve early risk stratification and clinical decision-making