Background: Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide, often complicated by acute exacerbations that impair lung function and quality of life. Effective airway clearance techniques are essential in managing exacerbations, but the comparative effectiveness of different methods remains unclear. This study aimed to evaluate the short-term effectiveness of TheraPEP, a positive expiratory pressure (PEP) device, versus the Active Cycle of Breathing Technique (ACBT) in managing acute COPD exacerbations. Methods: A randomized controlled trial (RCT) was conducted with 60 patients (≥40 years) admitted with acute exacerbations of COPD. Participants were randomly assigned to either the TheraPEP group (n=30) or the ACBT group (n=30). Each group received three daily sessions of their assigned therapy throughout their hospital stay. Primary outcomes included dyspnea, measured by the modified Borg Dyspnea Scale, and secondary outcomes included sputum clearance, lung function (FEV1, FVC, and FEV1/FVC ratio), oxygen saturation (SpO₂), and quality of life, measured by the Breathlessness, Cough, and Sputum Scale (BCSS). Data were collected at baseline, discharge, and 14-day follow-up. A two-way repeated-measures ANOVA was used to examine changes in dyspnea, lung function, sputum clearance, SpO₂, and BCSS scores over time (baseline, discharge, and 14-day follow-up) within and between groups. The main effects of time (within-subject factor) and group (between-subject factor) were assessed, along with the interaction effects (time × group). Results: Both groups demonstrated significant improvements in dyspnea, lung function, and quality of life from baseline to discharge and follow-up. However, the TheraPEP group showed significantly greater improvements in sputum clearance (p=0.01), oxygen saturation (p=0.03), and BCSS scores (p=0.03) compared to the ACBT group. No significant between-group differences were found for FEV1, FVC, or FEV1/FVC ratio (p > 0.05). Conclusions: Both TheraPEP and ACBT are effective in managing acute COPD exacerbations, but TheraPEP offers additional benefits in terms of sputum clearance and oxygenation. These findings suggest that TheraPEP may be more suitable for patients with severe mucus hypersecretion. Further research is warranted to assess the long-term effects of these therapies on COPD progression and patient outcomes.