OBJECTIVES: Missed nutrients from skipped meals affect diet quality. However, the extent to which breakfast skipping affects the inflammatory potential of a diet, as indicated by Children's Dietary Inflammatory Index (C-DII) score, remains unknown. We aimed to evaluate the association between breakfast skipping and C-DII score, and investigate the presence of interaction with sociodemographic factors and sedentary behavior. METHODS: This representative cross-sectional study enrolled 378 children ages 8 and 9 y from Viçosa, Minas Gerais, Brazil in 2015. We collected sociodemographic data (sex, age, race, and household per-capita income) and screen time using a semistructured questionnaire. Dietary intake and breakfast skipping were evaluated by three 24-h dietary recalls from which energy-adjusted C-DII scores were calculated. We performed linear regression models to test the associations and possible interactions. RESULTS: The prevalence of breakfast skipping and sedentary behavior were 20.1% and 47.6%, respectively. The mean ± standard deviation of the C-DII scores was 0.60 ± 0.94, and ranged from -2.16 (most anti-inflammatory diet) to 2.75 (most proinflammatory diet). Breakfast skipping was associated with a higher intake of lipids, monounsaturated fat, and polyunsaturated fat, as well as lower carbohydrate, calcium, and magnesium intake (P < 0.05). After adjustment, breakfast skippers had higher C-DII scores (ß = 0.33; 95% confidence interval, 0.12-0.54). This association was more pronounced in children with sedentary behavior (ß = 0.53; 95% confidence interval, 0.24-0.82). CONCLUSIONS: Breakfast skipping was associated with a more proinflammatory diet in school-age children, and there was significant interaction with sedentary behavior. Early childhood interventions encouraging the habit of eating a breakfast and engaging in physical activity may help reduce the dietary inflammatory potential and prevent related cardiometabolic disorders.