Objectives <p>The effects of mindfulness-based interventions associated with a high-intensity interval training (HIIT) program on mindfulness skills and well-being need further investigation. This randomized controlled trial (RCT) aimed to investigate the effect of a brief mindfulness meditation (BMM) intervention associated with a HIIT-based running program on mindfulness skills and well-being.</p> Method <p>Fifty-five runners were randomly assigned to BMM or control groups, combined with the same HIIT-based running program. The BMM group benefited from an 8-week BMM intervention. Mindfulness Inventory for Sport was completed at baseline (T₀), 4 (T₁), and 8&#xa0;weeks (T₂). The Diagnofeel, measuring the manifestations and regulations of well-being, was assessed at T₀ and T₂. A two-way repeated measures ANOVA was conducted.</p> Results <p>An overall increase of <i>awareness</i> was observed between T₀ and T₂. In terms of <i>refocusing</i>, a time*group interaction was discovered (<i>p</i> = 0.03, <i>η</i>^<i>2</i> = 0.07). <i>Refocusing</i> improved for the BMM group between T₀ and T₂ (<i>p</i> &lt; 0.01). The BMM group had a higher <i>refocusing</i> level compared to the control group at T₂ (<i>p</i> = 0.01). Regarding well-being, <i>social relation</i> (manifestation) and <i>pleasure</i> (regulation) increased between T₀ and T₂ in the BMM group.</p> Conclusions <p>This RCT showed the beneficial effects of a BMM intervention on the ability to quickly <i>refocus</i> attention on performance-related cues. These potential benefits could go beyond the athletic field, as the BMM intervention might positively impact the way that runners manifested and regulated their well-being in their daily lives.</p> Preregistration <p>The study was not preregistered.</p>