Teacher stress and burnout is a growing concern, which has been globally associated with high attrition rates and student outcomes. Research over the last few decades has sought to understand organisational and personal factors that contribute to burnout to explore and identify solutions to the problem of burnout. The current study investigated the effects of an online Acceptance and Commitment Therapy based (ACT) programme, Psyflex6 6, on psychological flexibility and the level of burnout among a sample of teachers in Australia. The results from between group and within group comparisons of an Experimental Group and Control Group (N = 6 and N =9, respectively) indicated that whilst not statistically significant, the Intervention Group experienced an increase in psychological flexibility, a decrease in psychological inflexibility, and a decrease in the level of burnout. It is possible that a larger sample may increase the statistical power to the findings and supporting the use of a self-administered online ACT intervention a possible approach to reduce burnout among teachers.