A Guided Ventilatory Maneuver (GVM) can lead to changes in the central and autonomic nervous systems. Chronic effects of GVM have been reported in the literature to enhance physical and mental health. Purpose: To investigate the immediate effects of GVM on cortical activity and cardiovascular activity. Method: Twenty healthy participants (age 18-30) were recruited. Eligibility for the study required no experience in any mindfulness training. Results: Measures of the study utilized electroencephalography and electrocardiogram to measure cortical and cardiovascular changes. The study provided support for acute effects of GVM on cortical dynamics and heart rate variability. Cortical activity exhibited an increase in cortical relaxation during GVM. And cardiovascular activity exhibited an increase in parasympathetic activity. Conclusion: The psychophysiological measures of this study provided evidence for GVM as a relaxation technique. Specifically, during GVM, participant’s cortical dynamics reflect an increase in relaxation.