People with significant health anxiety may experience brain‐gut dysregulation, leading to increased visceral sensitivity and greater gastrointestinal (GI) symptoms. Positive affect (PA), on the other hand, may serve as a protective characteristic, buffering the negative impact of health anxiety on GI symptoms. This study investigated interrelationships between health anxiety, PA, and GI symptoms. Longitudinal data were collected on health anxiety, PA, and GI symptoms via an online survey from 861 adults at two timepoints, 4 weeks apart. Regression models were conducted to examine the moderating effect of PA at baseline on future GI symptoms. Greater health anxiety at baseline predicted GI symptoms at follow‐up, whereas higher levels of PA predicted reduced GI symptoms at follow‐up. Post hoc testing revealed that PA significantly moderated the relationship between health anxiety and GI symptoms over time, such that higher levels of PA attenuated the effect of health anxiety on belly pain, nausea and vomiting, and reflux at follow‐up. This study provides preliminary evidence PA may buffer the negative impact of health anxiety on GI symptoms. Future studies should explore whether the promotion of PA through interventions similarly attenuates health related anxiety's impact on GI symptoms.