Use of controller asthma medication and possession of asthma action plans remains suboptimal. Our aim was to investigate the association of the propensity of physicians to involve patients in their care (participatory decision-making style) and their asthma management in a representative population sample of 3015 adults. Current doctor-diagnosed asthma was reported by 393 (13.0%). People who rated their doctors as more participatory were significantly more likely to report more regular use of controller medications and possession of a written asthma action plan, but not less asthma morbidity. Possession of a written action plan was associated with more participatory interactions (OR 2.3; 95% CI 1.1–4.7, for upper tertile scores compared to lowest tertile); more severe symptoms (OR 4.8; 95% CI 1.7–13.0), being female (OR 2.2; 95% CI 1.2–4.3), those with higher education, and residence outside the metropolitan area (OR 2.1; 95% CI 1.1–4.0). Increasing patient participation in their own care is associated with better asthma management, independent of asthma symptoms. Longitudinal studies are needed to examine if increasing participation in decisions can also improve asthma outcomes.