Background: Chronic obstructive pulmonary disease (COPD) is expected to rank third among the sixth largest leading causes of death by 2020 and sixth most debilitating condition. Positive expiratory pressure techniques such as flutter and blow bottle devices are usually used to improve respiratory function. Objective: The objective of this study is to compare the effect of blow bottle device and flutter device on functional capacity, dyspnea, fatigue, and peak expiratory flow rate (PEFR) in participants with mild-to-moderate COPD. Patients and Methods: Forty-five participants, between 40 and 70 years were screened for the study. Of these, 32 participants were included and 27 completed the study. They were classified into two groups. Group A was given blow bottle device and Group B flutter device. A 1-week intervention protocol was given to the participants. Results: There was a significant postintervention improvement in mean walking distance in both Group A and Group B, (128.07 ± 15.48 m to 141.53 ± 16.75 m, 163.92 ± 48.2 m to 177.64 ± 55.3 m), respectively, and in PEFR ([Group A 180 ± 83.46 L/min to 195.76 ± 92.91 L/min and in Group B 138.57 ± 39.39 L/min to 158.57 ± 33.30 L/min]). Dyspnea and fatigue decreased significantly postintervention in both groups. Conclusion: Both blow bottle and flutter devices are effective as adjunct therapy in the improvement of functional capacity, dyspnea, fatigue, and PEFR in participants with mild-to-moderate COPD. Flutter device is more effective in improving functional capacity, dyspnea, and fatigue, whereas the blow bottle device is more effective in increasing PEFR.