Abstract Background: Obesity-related cancers account for 40% of all cancers in the United States (U.S.). Healthy food consumption is a modifiable factor shown to reduce obesity-related cancer mortality, but residing in geographical areas with poor access to grocery stores/farmer’s markets (food deserts) or higher access to fast-food/convenience stores (food swamps) reduces healthy food access and has been severely understudied. Methods: We conducted an ecological study utilizing 2010 - 2020 data from the U.S. Department of Agriculture Food Environment Atlas and Center for Disease Control and Prevention mortality. 3,041 U.S. counties with complete information on food environment scores and obesity-related cancer mortality data were included. Food swamp score was calculated as the ratio of fast-food and convenience stores to grocery stores and farmer’s markets. Obesity-related cancer (based on the International Agency for Research on Cancer evidence between obesity and 13 types of cancer) mortality rates were categorized as high (≥71.8 per 100,000) versus low (<71.8 per 100,000) per county. We performed an age-adjusted multivariable polytomous logistic regression for the association between food desert scores, food swamp scores, and obesity-related cancer mortality rates. Results: Counties with high obesity-related cancer mortality rates had higher percentage of NH-black population (3.30 vs 1.80), persons older than 65 years (15.7 vs 15.4), poverty rates (19.0 vs 14.4), adult obesity rates (33.0 vs 32.1), and adult diabetes rates (12.5 vs 10.7) when compared to counties with low obesity-related cancer mortality (p-value < 0.0001; Table 1). We observed 77% increased odds of having high obesity-related cancer mortality rates among U.S. counties with high food swamp scores (adjusted odds ratio [AOR] = 1.77; 95% CI: 1.43 - 2.18). A positive dose-response relationship between three levels of food desert and food swamp scores and obesity-related cancer mortality was also observed (p-value <0.0001). Conclusions and Relevance: Policymakers, funding agencies, and community stakeholders should implement sustainable approaches at combating obesity and establishing healthier accessible food such as creating more walkable neighborhoods and community gardens. Citation Format: Malcolm Bevel, Meng-Han Tsai, April Parham, Sydney Andrzejak, Samantha R. Jones, Justin X. Moore. The association between food deserts, food swamps, and obesity-related cancer mortality in the United States: the new epidemic [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6483.