Caregivers of young people with borderline personality disorder (BPD) or BPD features experience significant burden and distress and often lack effective coping strategies. A family environment of pervasive invalidation can contribute to the disorder and work against effective coping. Consequently, some psychotherapy interventions for young people with BPD or BPD features aim to incorporate caregivers in treatment to varying degrees. This review synthesised results of existing studies that included caregivers in psychotherapy alongside their young person and that examined caregiver outcomes using quantitative measures. The review and literature search were conducted in accordance with PRISMA guidelines. Searches of five databases returned a total of 2988 articles, of which 10 met inclusion criteria and only two of which were RCTs. Seven used a dialectical behaviour therapy approach, two used brief psychoeducation, and one was an online social group. Articles examined changes in caregivers regarding treatment feasibility and satisfaction, emotion communication, perceived knowledge of BPD and caregiver mental health, burden and stress. Although there are few studies and results are limited by considerable methodological limitations, results suggest that including caregivers in treatment alongside young people, even in a brief capacity, may improve caregiver outcomes on several measures. Inclusion of caregivers is conceptually particularly pertinent for BPD for young people, and this review reveals important clinical implications and clear future research directions.