Despite its rare occurrence, severe mental illness is commonly linked to violence and crime in the news media. To reduce harmful effects of reporting, this study aimed to develop best practice guidelines for media reporting on mental illness in the context of violence and crime. Best practice was determined through the Delphi expert consensus method where experts rated statements according to importance for inclusion in the guidelines. In this study, the experts represented three groups: people with lived experience of severe mental illness, media professionals and mental health professionals. The 77 statements that were endorsed as ‘important’ or ‘essential’ by 80 per cent or more of experts were included in the guidelines, while 36 items were rejected from inclusion. There was a high degree of consensus among stakeholder groups. These guidelines expand on existing media guidelines, elaborating on accurate portrayals and appropriate language and extending coverage to areas of mental health literacy, considering impact, reporting relevant risk factors, using social media and implementation in news organizations.