BACKGROUND: Asthma remains a leading cause of hospitalization in US children. Well-child care (WCC) visits are routinely recommended, but how WCC adherence relates to asthma outcomes is poorly described. METHODS: We conducted a retrospective longitudinal cohort study using electronic health records among 5 to 17 year old children residing in Durham County with confirmed asthma and receiving primary care within a single health system, to compare the association between asthma exacerbations and previous WCC exposure. Exacerbations included any International Classification of Diseases, Ninth Revision, or International Classification of Diseases, 10th Revision, coded asthma exacerbation encounter with an accompanying systemic glucocorticoid prescription. Exacerbations were grouped by severity: ambulatory encounter only, urgent care, emergency department, hospital encounters <24 hours, and hospital admissions ≥24 hours. In the primary analysis, we assessed time to asthma exacerbation based on the presence or absence of a WCC visit in the preceding year using a time-varying covariate Cox model. RESULTS: A total of 5656 children met eligibility criteria and were included in the primary analysis. Patients with the highest WCC visit attendance tended to be younger, had a higher prevalence of private insurance, had greater asthma medication usage, and were less likely to be obese. The presence of a WCC visit in the previous 12 months was associated with a reduced risk of all-cause exacerbations (hazard ratio: 0.90; 95% confidence interval: 0.83-0.98) and severe exacerbations requiring hospital admission (hazard ratio: 0.53; 95% confidence interval: 0.39-0.71). CONCLUSIONS: WCC visits were associated with a lower risk of subsequent severe exacerbations, including asthma-related emergency department visits and hospitalizations. Poor WCC visit adherence predicts pediatric asthma morbidity, especially exacerbations requiring hospitalization.