Background: Despitethewidespread useof inhalation therapy, patients with chronic obstructive pulmonary disease (COPD) frequently experience suboptimal disease control dueto medication nonadherence, improper inhaler usetechnique, and inappropriate device selection, which collectively impair health-related quality of life (HRQoL). Pharmacist-led interventions may help address these gaps. Interventions based on the information-motivation-behavioral skills model and supported by digital toolscan improve adherence and self-management. This study evaluates the efficacy of a multifaceted pharmaceutical care intervention for COPD delivered through digital tool support. Objective: The primary objective is to comparethe change in HRQoL, measured using the St George's Respiratory Questionnaire, between the intervention and control groups from baseline to 12 months. Secondary objectives areto assess changes in medication adherence (Test of Adherenceto Inhalers), quality of life (EQ-5D-5L), COPD-related medical costs, and patient-reported pharmacy service experience. Methods: This 1-year cluster randomized controlled trial evaluates a multifaceted pharmaceutical care intervention in adults with moderate to very severeCOPD (Global Initiativefor Chronic Obstructive Lung Disease, stages 2-4) who have confirmed suboptimal inhaler practice but remain matched to an appropriate inhaler device based on peak inspiratory flow rate measured using a digital tool. In total, 34 hospital-based cough and wheeze pharmaceutical care clinics were recruited and randomized (1:1) to either an intervention or a control group. The target sample size is 15 patients per site. Participants in the intervention group will receivetailored support using electronic adherence monitoring, inhaler usetechnique assessments, and peak inspiratory flow rate to optimize device selection and self-management. Participants in the control group will receive usual pharmaceutical care. Descriptive statistics will be used to summarize participant characteristics and outcomes. Linear mixed effects models will be used to compare primary and secondary outcomes. Subgroup analyses will explore effects by age, sex, education level, place of residence, and smoking status. Pharmacy service survey data will be analyzed qualitatively. Results: The trial was registered on July 15, 2024. Recruitment started on November 9, 2024, and enrollment was completed by December 31, 2025. As of December 31, 2025, we enrolled 454 participants, of whom 16 (3.5%) had completed the 12-month follow-up. The trial is expected to be completed by December 31, 2026, with results planned for publication in 2027. Conclusions: This multifaceted, pharmacist-led pharmaceutical care intervention may provide a scalable model for improving COPD management and HRQoL. If effective, the digitally supported program, grounded in the information-motivation-behavioral skills model, could be implemented in more than 1000 cough and wheeze pharmaceutical care clinics nationwide.