The coronavirus disease 2019 (COVID-19) pandemic has increased the risk of psychological distress among adolescents. Moreover, adolescents in 70 countries have suffered simultaneously from the COVID-19 pandemic and flood disasters. Research on the protective role of mindfulness on psychological distress is warranted; moreover, the practical needs arising from disasters require a deeper understanding of the potentially complex interplay between mindfulness and psychological distress. Using social-ecological systems theory, this study examined the moderating effects of self-harm and negotiable fate on the relationship between mindfulness and psychological distress in adolescents suffering from concurrent dual disasters (COVID-19 and flood disasters). High school adolescents (N = 1679; 49.3% adolescent boys) in Zhengzhou, China, completed the Child and Adolescent Mindfulness Measure, Suicide Thoughts and Behaviors Checklist, Negotiable Fate Questionnaire, and Depression Anxiety Stress Scales-21. A three-way interaction model was developed. The results indicate that mindfulness has a significant negative relationship with psychological distress during disasters. Moreover, self-harm and negotiable fate significantly moderated the negative associations between mindfulness and psychological distress in adolescents enduring concurrent dual disasters (three-way interaction effects model). These findings highlight the significance of the interactions between different ecological system factors in the negative associations between mindfulness and psychological distress amid disasters.