Positive emotions help people recover from and adapt to stressors. In two studies we investigated the brain networks that support these beneficial effects that positive emotions have on stress regulation. In the first study, participants underwent an anagram stressor and reported on their emotional experiences while their BOLD signal was being measured using fMRI. We used change-point analyses to show that ventromedial prefrontal cortex (vMPFC) activity during the stressor predicted positive emotions during recovery, which in turn predicted decreased negative emotions during recovery. In the second study, participants underwent a social stressor in fMRI and reported on their emotional experience retrospectively. We used novel dynamic functional connectivity analyses to show that the vMPFC was the hub of a network whose functional connectivity during the stressor predicted retrospective positive emotions about that stressor. These studies highlight the vMPFC as a common participant of networks associated with positive emotions and emotion regulation such that it may serve as the hub through which positive emotions impact stress regulation. Also, these analyses highlight the utility of dynamically assessing neural activity throughout a stressor given that it was vMPFC activity and connectivity during the stressor and not during recovery that predicted positive emotional outcomes.