Unpaid carers form the backbone of health and care systems. Caregiving can be rewarding but can also diminish carer well-being. Many policies recognise that outcome-focused assessments are the foundation of effective support. In practice, carers can struggle to access these, preventing the realisation of carer-oriented policy goals. This systematic search and review explored literature concerning adult carer outcome assessment, retrieving 21 eligible studies spanning work in five countries. A narrative synthesis highlighted the skilled nature of the practice involved, alongside long-standing implementation barriers. We make evidence-based recommendations for policy implementation, with potential to improve outcomes for carers, practitioners and organisations.