Background: Accredited Exercise Physiologists (AEPs) are trained to deliver exercise and physical activity interventions for people with chronic and complex health conditions including those with mental illness. However, their views on exercise for mental illness, their exercise prescription practices, and need for further training are unknown. Aims: To examine the way in which Australian AEPs prescribe exercise for people with mental illness. Methods: Eighty-one AEPs (33.3 ± 10.4 years) completed an online version of the Exercise in Mental Illness Questionnaire. Findings are reported using descriptive statistics. Results: AEPs report a high level of knowledge and confidence in prescribing exercise for people with mental illness. AEPs rate exercise to be at least of equal value to many established treatments for mental illness, and frequently prescribe exercise based on current best-practice principles. A need for additional training was identified. The response rate was low (2.4%) making generalisations from the findings difficult. Conclusions: Exercise prescription practices utilised by AEPs are consistent with current best-practice guidelines and there is frequent consultation with consumers to individualise exercise based on their preferences and available resources. Further training is deemed important.