BACKGROUND Little is known about adolescents' food purchasing behaviors in rural areas. This study examined whether purchasing food at stores/restaurants around schools was related to adolescents' participation in school breakfast programs and overall diet in rural Minnesota. METHODS Breakfast‐skippers enrolled in a group‐randomized intervention in 2014 to 2015 (N = 404 from 8 schools) completed 24‐hour dietary recalls and pre/post surveys assessing food establishment purchase frequency. Healthy Eating Index Scores (HEI‐2010) were calculated for each student. Student‐level school breakfast participation (SBP) was obtained from school food service records. Mixed‐effects regression models estimated: (1) whether SBP was associated with store/restaurant use at baseline, (2) whether an increase in SBP was associated with a decrease in store/restaurant use, and (3) whether stores/restaurant use was associated with HEI‐2010 scores at baseline. RESULTS Students with increased SBP were more likely to decrease fast‐food restaurant purchases on the way home from school (OR 1.017, 95% CI 1.005, 1.029), but were less likely to decrease purchases at food stores for breakfast (OR 0.979, 95% CI 0.959, 0.999). Food establishment use was associated with lower HEI‐2010 dairy component scores (p = .017). CONCLUSIONS Increasing participation in school breakfast may result in modest changes in purchases at food establishments.