The present study examined the differences in frontal EEG asymmetry during emotion regulation between participants who had different levels of trait mindfulness. EEG recordings were taken from 23 high mindfulness adolescents (M-age = 12.34) and 22 low mindfulness adolescents (M-age = 12.53) during the Reactivity and Regulation-Image Task. The results showed that (1) high mindfulness adolescents had greater left (relative to right) asymmetry than low mindfulness adolescents in down-regulation and up-regulation conditions; however, there was no significant difference in the non-regulation condition; (2) In the up-regulating condition, adolescents showed greater right (relative to left) asymmetry for negative stimuli compared to neutral stimuli; however, there was no significant difference in down-regulation and non-regulation conditions. The results provide neurological evidence that trait mindfulness was highly related to the regulation of emotions and affects how emotions are processed.