Asthma and chronic obstructive pulmonary disease (COPD) are long-term lung diseases that make it hard for air to circulate and cause breathing problems. Following the doctor's instructions for inhaler medication and using the right method for inhalation are both important for good illness management and control. Patients with asthma and COPD often don't follow their treatment plans or use the wrong breathing method, which makes their therapy less effective and puts more strain on the healthcare system. To examine the effects of a pharmacist-led intervention on inhaler adherence, inhalation technique, and disease management in patients with asthma and COPD. Patients and Methods: A pre-post interventional design evaluated the impact of pharmacist-led intervention on inhaler adherence, inhalation methods, and disease management in asthma and COPD patients at Dhulikhel Hospital, Nepal. Inclusion criteria: adult patients clinically diagnosed with asthma or COPD of either gender. The strategy included coaching patients using tools such as movies and educational pamphlets. The checklist method for inhalation technique, the Test of Adherence to Inhaler (TAI) questionnaire for adherence to inhaler, and the "Asthma Control Test (ACT)" or "COPD Assessment Test (CAT)" for disease control were used to assess impact. The pharmacist-led intervention substantially enhanced adherence to inhalers, as shown by a marked increase in the percentage of patients demonstrating strong adherence (P<0.001). The patterns of sporadic, purposeful, and unintentional noncompliance also improved considerably following the intervention (P<0.001, P<0.001, and P=0.001). The inhalation method showed a significant improvement after the intervention (P<0.001). The analysis revealed significant moderate negative correlations between “TIA” and “CAT” [ρ=−0.31; P=0.01], and between “inhalation technique score” and “CAT score” [ρ=−0.31; P=0.01]. This suggests that as adherence to inhaler usage and inhalation technique improves, CAT scores tend to decrease, indicating a reduced impact of the disease on the patient. This research demonstrates the potential effectiveness of pharmacist-led interventions in improving adherence to inhaler use, inhalation techniques, and disease management in respiratory disorders including asthma and COPD.