The present study investigated whether engaging in a mindful breathing exercise would affect EEG oscillatory activity associated with self‐monitoring processes, based on the notion that mindfulness enhances attentional awareness. Participants were assigned to either an audio exercise in mindful breathing or an audio control condition, and then completed a Stroop task while EEG was recorded. The primary EEG measure of interest was error‐related alpha suppression (ERAS), an index of self‐monitoring in which alpha power is reduced, suggesting mental engagement, following errors compared to correct responses. Participants in the mindful‐breathing condition showed increased alpha power during the listening exercise and enhanced ERAS during the subsequent Stroop task. These results indicate enhanced error‐monitoring among those in the mindful‐breathing group.