The current study aimed to examine the mechanism of the association between dispositional mindfulness and adolescent mental health (depression, anxiety, and stress) in a longitudinal design, considering the mediating effect of attentional control and the moderating effect of self-esteem. A sample of 1150 adolescents (M/SDage = 15.96/0.97 years, 55% female) completed self-report measures of dispositional mindfulness and mental health at T1, attentional control and self-esteem at T2, and mental health at T3 (baseline T1; three-month follow-up T2; six-month follow-up T3). After controlling for gender, age and mental health at T1, results showed that dispositional mindfulness at T1 negatively predicted depression, anxiety and stress at T3, and attentional control at T2 mediated this association. Furthermore, self-esteem at T2 moderated the pathway from attentional control at T2 to depression at T3 in the mediated model. Specifically, the association between attentional control and depression was stronger in adolescents with low self-esteem. Limitations and implications for prevention and intervention are discussed.