Background Most of the studies involving members of the Seventh-Day Adventist Church (SDA) have been conducted in the United States and Canada. Aim The purpose of the study was to explore the relationship between dietary self-efficacy and religiosity among SDA members in Peru. Methods In this online cross-sectional study, 403 participants aged 18 to 59 years selected by convenience were included. The data collected included sociodemographic information. In addition, the Dietary Self-Efficacy Scale (DIET-SE) and the Duke University Index of Religion (DUREL) were administered. A correlation analysis was performed and multiple linear regression was used to examine the association between religiosity, dietary self-efficacy, and sociodemographic variables. Results Dietary self-efficacy was significantly negatively correlated with all dimensions of religiosity, ie, organized religious activities (ORA), non-organized religious activities (NORA), and intrinsic religiosity (IR). In addition, participants had high dietary self-efficacy and religiosity. Conclusion Although religiosity dimensions did not significantly predict dietary self-efficacy, however, the non-organized religious activities dimension was the strongest predictor of dietary self-efficacy among Adventists in Peru. The present study will serve as a basis for future research to further investigate the potential positive effect of religiosity on the improvement a healthy diet and possible changes in the physical and mental health of the population.