Purpose: To examine the moderating role of mastery in the association of local fast-food restaurants (FFR) with diet quality and systolic blood pressure (SBP). Methods: We used cross-sectional data from 1543 adults participating in wave six of the Netherlands Study of Depression and Anxiety (NESDA). Data were collected between 2013 and 2016. Diet quality was defined by adherence with the dietary approaches to stop hypertension (DASH) diet. Individuals reported on their food consumption through a food frequency questionnaire and SBP was measured. Density of FFR in 1600 m, 800 m and 400 m circular buffers around the home postal code was calculated using Geographic Information Systems. We assessed the association between density of FFR, diet and SBP using linear regression analyses, testing for moderation by mastery. Results: Mean age was 52 years and 32.2% of the sample were men. Exposure to FFR ranged from 0 to 35 FFR per km2. Density of FFR was not significantly associated with DASH adherence or SBP. Only one out of the six interaction terms was significant, suggesting that for individuals with lower levels of mastery, higher density of FFR in an 800-m buffer was negatively associated with DASH adherence, while for individuals with higher levels of mastery, this association was positive. Conclusions: Exposure to FFR was not associated with diet quality and SBP, and we observed little evidence for moderation by level of mastery. This research question should be further explored in a large sample of healthy adults.