Summary Forensic social work is the application of social work knowledge, skills, values and ethics within a legal and criminal justice context. Globally, social workers play an integral role in the criminal justice system but in many countries, including Australia, there is limited conception of the competencies needed for this specialist practice. Australia serves as an example of forensic social work regulated through a generalist social work competency framework, where specialist skills and knowledge are not distinctly outlined or assessed. The purpose of this study was to identify the knowledge and skills used by forensic social work practitioners in Australia. This study used a 3-round Delphi method with an expert panel of social workers working in forensic practice across Australia. It consisted of a 1-hour semi-structured individual interview followed by 2 rounds of online surveys. Findings Consensus was obtained for 30 skill and knowledge items for Australian forensic social work. The panel identified these competencies as specialist, meaning requiring further training beyond generalist proficiency. Of these, eight of the skill and knowledge items were seen as essential for graduates entering forensic social work. Applications The findings from this study contribute to an evidence-based model of forensic social work competency. In Australia, they can be used to consider potential gaps between current generalist mechanisms and specialist practice expectations. With further research, these findings can be used to inform professional standards for forensic social work in Australia and potentially internationally.