Background Latin America ranks among the regions with the highest level of intake of sugary beverages in the world. Innovative strategies to reduce the consumption of sugary drinks are necessary. Purpose Evaluate the effect of a one-off priest-led intervention on the choice and preference of soda beverages. Methods We conducted a pragmatic cluster-randomized trial in Catholic parishes, paired by number of attendees, in Chimbote, Peru between March and June of 2017. The priest-led intervention, a short message about the importance of protecting one’s health, was delivered during the mass. The primary outcome was the proportion of individuals that choose a bottle of soda instead of a bottle of water immediately after the service. Cluster-level estimates were used to compare primary and secondary outcomes between intervention and control groups utilizing nonparametric tests. Results Six parishes were allocated to control and six to the intervention group. The proportion of soda selection at baseline was ~60% in the intervention and control groups, and ranged from 56.3% to 63.8% in Week 1, and from 62.7% to 68.2% in Week 3. The proportion of mass attendees choosing water over soda was better in the priest-led intervention group: 8.2% higher at Week 1 (95% confidence interval 1.7%–14.6%, p = .03), and 6.2% higher at 3 weeks after baseline (p = .15). Conclusions This study supports the proof-of-concept that a brief priest-led intervention can decrease sugary drink choice.