Mindfulness meditation is a means of increasing awareness of the present moment. Mindfulness Mediation Interventions (MMI) positively impact psychological functioning, yet the neurocognitive mechanisms that mediate these effects have been less well-defined. Here, the primary aim was to evaluate whether the effects of a 10-week MMI were mediated by changes in attention and creativity performance, as well as resting-state theta/beta (TB) ratio and alpha power. We also sought to determine whether any of these measures at baseline were predictive of mindfulness success, as rated by the 7–11-year-old participants and their teachers. Reductions in depression from pre-to-post were mediated by reductions in TB ratio and increases in alpha power; however, they were not mediated by attention/creativity changes. Higher baseline attention and creativity scores predicted enhanced mindfulness success post-intervention but notably, follow-up analyses revealed that those scoring lower on these measures were more likely to have reduced depression from pre-to-post.