Children today face increasingly high stress levels, impacting their well-being. Schools can play a crucial role in teaching social and emotional skills; therefore there is a need to identify effective interventions. This mixed-methods study of 124 elementary school students from three New Zealand schools aimed to (1) assess if children experienced improved well-being after an eight-week mindfulness program, and (2) understand their perceptions of the program. Participants completed these self-rated scales: the Mindful Awareness Attention Scale for Children and the Stirling Children’s Well-being Scale. Six children were interviewed about their perceptions and classroom teachers’ observations were reviewed. Quantitative data indicated a steady increase in students’ mindfulness, while well-being increased significantly but returned to baseline levels at three-month follow up. Changes in mindfulness were positively related to changes in well-being. The study results suggest the importance of offering mindfulness-based programs for potential improvements in students’ well-being.