Mindfulness has been linked with decreased psychological distress, yet little is known about the possible intervening variables to explain this link. The aim of this study was to investigate the contribution of attachment styles and emotion regulation in explaining the relationship between mindfulness and psychological distress. It was hypothesised that mindfulness would be inversely associated with psychological distress, and that attachment style (attachment anxiety and attachment avoidance) and emotion regulation would mediate this relationship. Australian adults (N = 402) completed an online questionnaire assessing mindfulness, emotion regulation, attachment style, and current psychological distress. Bootstrap mediation analyses confirmed an inverse relationship between mindfulness and distress. Both attachment anxiety and emotion regulation deficits were found to mediate the association between mindfulness and distress; however, attachment avoidance was not found to have a mediating effect. The findings are the first to demonstrate that attachment anxiety and emotion regulation deficits, in part, explain the association between mindfulness and various indicators of psychological distress. These findings highlight factors that may be useful to focus on within psychosocial interventions addressing psychological distress.