Objectives: Emotional dysfunction has historically been neglected in research exploring psychosis. This study presents evidence for understanding emotional distress and psychotic symptomatology under the developmental frameworks of attachment theory and emotion regulation. Design: The study used a cross-sectional design, using correlational and mediation analysis. Method: Fifty-one individuals who met the criteria for a psychotic disorder and whose acute psychotic symptoms were in remission, completed measures of attachment style, emotion regulation, distress (depression, anxiety and stress), and severity of psychotic symptoms. Results: Consistent with expectation, attachment style was associated with affective and psychotic symptomatology. There was evidence of mediation in the relationship between secure attachment and depression, and between secure attachment and hallucinations, through less dysfunctional emotional regulation. More dysfunctional emotional regulation was also found to mediate the relationship between fearful attachment style and depression, and hallucinations. Partial mediation was observed between dismissing attachment and positive symptoms through greater use of internal strategies. Conclusions: An insecure fearful attachment style can leave individuals vulnerable to dysfunctional emotion regulation. Consequently, individuals may experience elevated emotional distress and more severe positive symptoms. Furthermore, secure attachment appears to be a protective factor against the severity of affective and psychotic symptomatology due to less dysfunctional emotional regulation.