Objectives: Paranoia describes unfounded and distressing interpersonal threat beliefs. Secure attachment imagery has been shown to attenuate paranoia and anxiety in non‐clinical and clinical groups, but little is known about the differential effects of anxious and avoidant imagery or mechanisms of change. In this study, we tested the impact of secure, anxious, and avoidant attachment imagery on paranoia, anxiety, and help‐seeking intentions. We also examined hypothesized mechanisms of change, specifically whether cognitive fusion and negative self‐ and other‐beliefs mediate these relationships. Design: This study utilized an experimental, cross‐sectional design. Methods: A large (N = 303), international general population sample with high levels of non‐clinical paranoia completed a series of measures before and after engaging in secure, anxious, or avoidant imagery. Results: Relative to anxious and avoidant attachment imagery, secure attachment imagery reduced paranoia and anxiety and increased help‐seeking intentions. Cognitive fusion and negative self‐ and other‐beliefs mediated the impact of attachment imagery on paranoia and anxiety, but not help‐seeking. Conclusions: In line with attachment and cognitive theory, secure attachment imagery is effective in reducing paranoia and anxiety and works by reducing cognitive fusion and negative self‐ and other‐beliefs. These novel findings suggest that the secure imagery task could be incorporated into cognitive and behavioural therapies to reduce distressing interpersonal threat beliefs and associated negative affect, and increase help‐seeking intentions. Practitioner points: When working with people experiencing paranoia, secure attachment imagery may be effective in reducing state paranoia and anxiety and improving help‐seeking intentions.Attachment imagery works by influencing beliefs about self and others, and the degree to which people are fused with their beliefs. In clinical practice, the rationale for the imagery task fits well with psychological models of paranoia and the secure imagery task can be introduced as a way to cope when struggling with distressing beliefs about self and others, and feeling overwhelmed by these fears. [ABSTRACT FROM AUTHOR]