This study aimed to develop a framework for improved legislation, methods of practice and services used to meet the best interest of child offenders with psychiatric disorders within the South African child justice system. This aim was achieved via a qualitative study, which evaluated child justice and mental health legislation, methods of practice, role-players, and services in South Africa, and compared same to those in Namibia, Botswana, and Nigeria; to establish if the best interest of child offenders with psychiatric disorders are currently met from a South African perspective. Data collection occurred in two phases: a document analysis of legislation, policies, and procedures in the selected comparative jurisdictions; followed by semi-structured interviews with child justice and mental health experts. During phase one the researcher analysed child justice and mental health legislation, human rights protections, and policy related to child justice in Nigeria, Botswana, Namibia, and South Africa. In addition, she interrogated literature relating to child justice and mental health, in comparative jurisdictions. This phase formed the foundation for the semi-structured interview schedule. Purposive and theoretical sampling was used to conduct 24 semi-structured interviews. Data was analysed and interpreted using pure qualitative document and thematic analysis. The overarching findings indicate that the best interest of child offenders with psychiatric disorders, in the South African child justice system, are unprotected. This vulnerable group is not dealt with from an individualised, case-specific, multi-disciplinary perspective; informed by legislation, practice-policy, and a service-orientated approach. Further, certain domestic legislation and methods of practice are inadequate in holistically assessing a child who comes into conflict with the law in the jurisdictions of comparison. Further findings identified that biological, psychological, environmental, cultural, and social factors influence the development of psychiatric disorders in children, which may bring them into conflict with the law. This study further confirmed that Attention Deficit Hyperactivity Disorder, Intellectual Development Disorder, Learning Disorder, Oppositional Defiant Disorder, and Conduct Disorder are prevalent in children who iv come into conflict with the law. Further, substance abuse disorder, depression and attachment disorder were identified as predominant factors affecting children who come into conflict with the law. The influence of these factors, in conjunction with biological, psychological, environmental, cultural, and social factors, were found to predispose children to psychiatric disorders linked to criminal behaviour. Thus, to meet the best interest standard; children in conflict with the law must be dealt with using a multi-factorial approach which considers biological, environmental, social, cultural, and psychological factors. In this way, the behaviour of child offenders with psychiatric disorders will be addressed holistically in a manner that considers all factors influencing behaviour. The empirical data supported the recommendations used to develop a trans-disciplinary framework for child offenders with psychiatric disorders.