Police diversion is widely utilised as an intervention for minor cannabis offending in Australia. This study compared the cost-effectiveness and outcomes of three kinds of diversions—cautions, expiation and warnings—with the traditional criminal justice system response of charging the offender. A sample of 998 people who had recently had contact with police for cannabis use or possession completed a purpose built online survey that examined resource use and health, social and offending outcomes. It showed that those who were diverted reported less disruptive relationships, fewer employment problems and more positive perceptions of police legitimacy, without leading to higher levels of drug use or offending. Moreover, cannabis diversion cost six to 15 times less than a criminal charge. The study supports previous findings that diversion for minor cannabis offences can save money and lead to better social consequences. These results provide additional evidence for continuing and expanding police drug-diversion programs in Australia and abroad.