Sub-optimal chronic obstructive pulmonary disease (COPD) management has been found largely due to patients’ medication non-adherence and incorrect inhaler technique. This study aimed to examine inhaler use technique and medication adherence among Vietnamese COPD patients as well as potential associated factors. A cross-sectional study involving 70 COPD exacerbators was conducted. Inhaler technique and adherence were evaluated by the 10-item and 12-item Test of Adherence to Inhaler (TAI). Data on the history of COPD, home prescription of inhalers and duration of hospitalization were also collected. Generalized linear regression models were used to determine the associated factors with inhaler use and medication adherence. The results showed that the proportion of patients with good inhaler technique was 22.7% for metered-dose inhalers (MDI), 30.4% for dry powder inhalers (DPI) and 31.8% for soft-mist inhalers (SMI). Full exhalation was the most common mistake. The rates of non-compliance patterns were: “ignorant” (77.1%), “sporadic” (58.6%), and “deliberate” (55.7%). Worse dyspnea, greater health condition impairment, and an increased frequency of exacerbations and hospitalizations were found to be associated negatively with correct inhaler use and treatment adherence. Instructions to COPD patients about using inhalers should focus on correct inhaler technique and adherence even when feeling healthy.