To compare adherence to once-daily umeclidinium/vilanterol (UMEC/VI), a long-acting muscarinic antagonist/long-acting β2-agonist (LAMA/LABA), and twice-daily inhaled corticosteroids (ICS)/LABA single-inhaler dual therapy in patients with chronic obstructive pulmonary disease (COPD) in a primary care cohort in England. Active comparator, new-user, retrospective cohort study using CPRD-Aurum primary care data and linked Hospital Episode Statistics secondary care administrative data. Patients without exacerbations in the previous year were indexed on first/earliest prescription date of once-daily UMEC/VI or twice-daily ICS/LABA as initial maintenance therapy between July 2014-September 2019. Primary outcome: medication adherence at 12 months post-index, defined as proportion of days covered (PDC) ≥80%. PDC represented proportion of time over the treatment duration that the patient was theoretically in possession of the medication. Secondary outcomes: adherence at 6, 18, and 24 months post-index, time-to-triple therapy, time-to-first on-treatment COPD exacerbation, COPD-related and all-cause healthcare resource utilization (HCRU), and direct health-care costs. A propensity score was generated and inverse probability of treatment weighting (IPTW) was used to balance potential confounders. Superiority was defined as >0% difference between treatment groups. In total, 6815 eligible patients were included (UMEC/VI:1623; ICS/LABA:5192). At 12 months post-index, weighted odds of a patient being adherent were significantly greater with UMEC/VI versus ICS/LABA (odds ratio [95% CI]: 1.71 [1.09, 2.66]; p=0.0185), demonstrating superiority of UMEC/VI. Patients taking UMEC/VI were statistically significantly more adherent than those taking ICS/LABA at 6, 18, and 24 months post-index (p<0.05). Differences in time-to-triple therapy, time-to-moderate COPD exacerbations, HCRU, and direct medical costs were not statistically significant between treatments after IPTW was applied. At 12 months post-treatment initiation, once-daily UMEC/VI was superior to twice-daily ICS/LABA in medication adherence among patients with COPD without exacerbations in the previous year, newly initiating dual maintenance therapy in England. The finding was consistent at 6, 18, and 24 months.