Abstract Background Mindfulness programmes as a potential avenue of enhancing pupil wellbeing are beginning to show great promise. However, research concerning the effectiveness of mindfulness training for primary aged school children (7–11 years of age) has been neglected. Methods Building on methodological limitations of prior research, this study employed an active controlled design to assess the longer term wellbeing and emotion regulation outcomes after a 6 week mindfulness programme (Living Mindfully Programme, UK), for a group of school children aged between 9 and 10. The programme was delivered by class teachers as part of their normal curriculum entitlement. One hundred and eight children took part from across three schools in North East of England. Participants formed a treatment group (n = 64), active control (n = 19) and wait list control (n = 25). Self-report measures of wellbeing, mindfulness and emotion regulation were collected at pre and post training as well as at 3 months follow up. Results Reliable findings, judged by medium to large effect sizes across both post intervention, follow-up and between both controls, demonstrated enhancement in a number of domains. Immediately after training and follow up, when compared with the wait list control, children who received mindfulness training showed significant improvements in mindfulness (d = .76 and .77), Positive Outlook (d = .55 and .64) and Life Satisfaction (d = .65 and 0.72). Even when compared to an active control, the effects remained although diminished reflecting the positive impact of the active control condition. Furthermore, a significant positive relationship was found between changes in mindfulness and changes in cognitive reappraisal. Conclusions Taken together, this study provides preliminary evidence that the Living Mindfully Primary Programme is feasibly delivered by school staff, enjoyed by the children and may significantly improve particular components of wellbeing. Importantly, higher levels of mindfulness as a result of training may be related to effective emotional regulatory and cognitive reappraisal strategies.