This three-wave longitudinal study examined the relationship between dispositional mindfulness and adolescent mental health problems (depression, anxiety, and stress) by testing the mediating role of attentional control and the moderating role of self-esteem. 1150 adolescents (M/SDage = 15.96/0.97 years, 55% female) completed a self-report questionnaire on dispositional mindfulness and mental health problems at T1 (baseline), attentional control and self-esteem at T2 (three-month follow-up), and mental health problems at T3 (six-month follow-up). Results showed that dispositional mindfulness at T1 negatively predicted mental health problems at T3, and attentional control at T2 mediated this association. In addition, self-esteem at T2 moderated the pathway from attentional control at T2 to depression at T3, suggesting that attentional control has a stronger predictive effect on depression in adolescents with low self-esteem. The findings highlight attentional control as a key mechanism of dispositional mindfulness in alleviating mental health problems, particularly for adolescents with low self-esteem. Implications for prevention and intervention in adolescent mental health problems are discussed.