The aim of the study was to examine effects of the Mindfulness-Acceptance-Commitment (MAC) programme on sport-specific dispositional mindfulness, sport anxiety, and experiential acceptance, compared to an inactive control group, in a population of Martial Arts (MA) athletes. Twenty-three MA athletes were subjected to the MAC intervention, and 22 MA athletes comprised the control group. To analyse potential differences in the outcome variables between the two groups, Bayesian repeated measures analysis of variance (RM-ANOVA) was used. Findings showed that the MAC-group had greater increases over time in the sport-specific mindfulness subscales awareness and acceptance and acceptance, compared to the control group. In contrast, no interaction effects were found for present moment attention (AMQ), experiential acceptance (BEAQ), and sport anxiety (SAS-2). Overall, the present study adds further information and understanding about the effectiveness and implementation of the MAC programme.