Despite the growing body of cross-sectional research linking burnout and mindfulness, hardly any research has investigated the longitudinal relationship between these two constructs during the pandemic. The purpose of this research was to examine the bidirectional association between COVID-19 burnout and mindfulness in counsellor candidates. We employed a two-wave longitudinal design among Turkish counsellor candidates (M = 21.10, SD = 2.10). They completed the Mindful Attention Awareness Scale and the COVID-19 Burnout Scale. The cross-lagged analyses showed that COVID-19 burnout predicted longitudinal decreases in mindfulness. On the contrary, mindfulness did not predict changes in counsellor candidates' COVID-19 burnout. These findings highlight the importance of targeting COVID-19 burnout in increasing mindfulness over the long-term.