To what degree do cognitively based strategies of emotion regulation impact subsequent cognitive control? Here, we investigated this question by interleaving a cognitive task with emotion regulation trials, where regulation occurred through cognitive reappraisal. In addition to obtaining self-reports of emotion regulation, we used the late positive potential (LPP) of the event-related brain potential as an objective index of emotion regulation. On each trial, participants maintained, decreased, or increased their emotional response to an unpleasant picture and then responded to a Stroop stimulus. Results revealed that (1) the magnitude of the LPP was decreased with reappraisal instructions to decrease negative emotion and were enhanced with reappraisal instructions to increase negative emotion; (2) after cognitive reappraisal was used to increase the intensity of negative emotion, RT interference in the subsequent Stroop trial was significantly reduced; and (3) increasing negative emotions by reappraisal also modulated the cognitive control-related sustained potential. These results suggest that increasing negative emotions by cognitive reappraisal heightens cognitive control, which may be sustained for a short time after the regulation event.