This study investigated the relationship among parent and peer attachments, dispositional mindfulness, and psychological distress, and tested the mediating role of dispositional mindfulness between attachments and psychological distress. A sample of 938 Chinese secondary school students participated in the study. Results showed that: (a) both attachments and dispositional mindfulness were negatively associated with psychological distress; (b) dispositional mindfulness could partially mediate the relations between attachments and psychological distress; (c) the mediation effect from parent attachment through mindfulness to psychological distress was stronger than that from peer attachment. The results suggest that attachment, especially parent attachment, is helpful in enhancing students’ dispositional mindfulness, which in turn reduces psychological distress in secondary school students. Some implications about how to enhance attachment and reduce psychological distress through mindfulness were discussed.