Background/Question/Methods Biodiversity conservation and human food security (the right of access to sufficient healthy food) appear to represent a large-scale, high-stakes example of the fundamental ecological principle of trade-offs: the use of resources for agricultural expansion and intensification is a major driver of global biodiversity loss, but as many as a billion people still suffer from malnourishment. However, in a case study of the city of Belo Horizonte, Brazil, I found evidence that a radical increase in local food security also correlated to higher biodiversity on local farms and their associated forest fragments in the surrounding megabiodiverse Atlantic rainforest region. I examined this dynamic by sampling ground-foraging ant species on farms that directly participated in Belo Horizonte’s food security programs, and comparing biodiversity on these farms to similar farms in the same region that did not take part in the programs. This sampling, along with semi-structured interviews of farmers and staff members of Belo Horizonte’s city government, allowed me to explore how food security influenced biodiversity, mediated through the city's work with local farmers. Results/Conclusions My results showed a positive but subtle effect of participation in the city food programs on the ground-foraging ant community of local farms. Higher beta diversity was found within sampled participating farms versus non-participating farms in the same region. Additional analysis indicated higher alpha diversity and ant abundance on participating farms, as well as higher similarity between the farm field and rainforest fragment ant community as compared to non-participating farms. My findings of positive effects on biodiversity are backed by data from interviews indicating that partner farmers feel more economically secure, grow more diverse crops, use less pesticides, and receive better technical advising, factors that have been previously linked to better matrix quality and higher biodiversity within the extant literature. The structure of Belo Horizonte’s programs also provides unique opportunities to further strengthen the connections between food security and sustainable practices in order to better support biodiversity. This case study may be the first to directly link biodiversity conservation with food security and changes in local food policy institutions, emphasizing the importance of a political ecological approach and the potential for human well-being and conservation to go hand-in-hand.