Background: Both atopic dermatitis and celiac disease are often accompanied by other immune-mediated disorders. Objective: The objective of this study was to evaluate the potential association between atopic dermatitis and celiac disease in a broad community-based population. Methods: A cross-sectional observational design was used. Demographic and clinical data were collected for patients enrolled in a large health management organization who were diagnosed with atopic dermatitis by a dermatologist in 2002–17. The presence of celiac disease/celiac disease-related morbidities was recorded for the whole group, for adults (age > 18 years), and for adults with moderate-to-severe atopic dermatitis. Findings were compared with a matched control group without atopic dermatitis. Results: The study group included 116,816 patients of whom 45,157 were adults; 1909 adult patients had moderate-to-severe atopic dermatitis. Compared to the respective control subjects, the prevalence rate of celiac disease in the whole group was 0.6% vs. 0.4%; in the adults, 0.6% vs. 0.3%; and in the adults with moderate-to-severe atopic dermatitis, 0.8% vs. 0.3% (p < 0.001 for all). On multivariate analysis, atopic dermatitis was associated with a significantly higher prevalence of celiac disease (odds ratio = 1.609, 95% confidence interval 1.42–1.82, p < 0.001) in the entire study population and each subgroup. Conclusions: We observed a significant association between atopic dermatitis and celiac disease. This association emphasizes the need for timely screening of gastrointestinal morbidities in individuals with atopic dermatitis to prevent long-term complications.