Background Beclometasone dipropionate is an inhaled corticosteroid (ICS) available in both extrafine and larger-particle hydrofluoroalkane formulations. Extrafine beclometasone has greater small airway distribution and inhalation technique tolerance than larger-particle beclometasone; therefore, its use may be associated with improved asthma outcomes at population levels. The study objective was to compare real-life effectiveness of extrafine and larger-particle beclometasone. Methods Retrospective matched cohort study including primary care patients with asthma (ages 12–60 and non-smokers 61–80 years) prescribed extrafine or larger-particle beclometasone by metered-dose inhaler. We studied patients receiving their first ICS (initiation population, n = 11,289) or switched from another ICS without dose change (switch population, n = 19,065). The extrafine and larger-particle beclometasone cohorts were matched in each population for demographic and database measures of asthma control during a baseline year; and endpoints assessed during 1 outcome year were adjusted for residual confounding factors. Results The odds of no loss of asthma control (no asthma-related hospital attendance, consultation for lower respiratory tract infection, or oral corticosteroids) were significantly higher in the extrafine beclometasone cohorts of both initiation population (adjusted odds ratio [aOR] 1.12; 95% CI 1.02–1.23) and switch population (aOR 1.10; 95% CI 1.01–1.19). The odds of better adherence to ICS therapy were also significantly higher in both extrafine beclometasone cohorts (initiation population, aOR 1.64; 95% CI 1.52–1.75 and switch population, aOR 1.35; 95% CI 1.27–1.43). Conclusions These findings are consistent with the hypothesis that delivery of beclometasone in extrafine particle size produces real-life asthma treatment benefits.