Empirical research has demonstrated associations between heart rate variability (HRV) and the regulation of emotion and behavior. Similarly, self-regulation of attention to one’s experience of the present moment in an accepting and nonjudgmental manner is an essential characteristic of mindfulness that promotes emotional and behavioral regulation and psychological well-being. The present study investigated the relationship between mindfulness and HRV. A total of 23 undergraduate psychology students completed a recently developed measure of mindfulness, the mindful breathing exercise (MBE), which assesses the ability to mindfully stay in contact with one’s breath during breathing meditation. Moreover, indices of HRV were measured during a short version of the MBE. As predicted, positive correlations were found between indices of HRV and mindfulness. The findings demonstrate that the ability to mindfully regulate one’s attention is associated with higher HRV, a physiological correlate of physical and psychological health, and therefore support on a physiological level the potential benefit of the implemented mindfulness exercises in mindfulness-based clinical interventions.