Offenders with personality disorder cause disproportionate harm to society and pose significant challenges for those responsible for their care and rehabilitation. Personality disorders are heterogeneous in terms of symptoms, as well as their pathways to offending behaviour. Thus, there is limited evidence regarding effective interventions. One solution might be to focus on how interventions are delivered as well as what is delivered. Within the non‐offender personality disorder literature, the identification of potential mediators of change has enabled interventions to focus on ‘how’ they are delivered (e.g., therapeutic alliance) rather than the intervention itself. We explore the evidence and present a scoping review of the available literature on the mechanisms of change in psychological treatments for offenders with personality disorder. Only one study was found in the scoping review, highlighting a significant gap in the evidence base. We discuss the implications of this finding and potential future directions.