Background: This study describes the development of a system dynamics model to project the potential impact of a series of proposed suicide prevention interventions in New South Wales (NSW, Australia) over the period 2016 to 2031. Methods: A system dynamics model for the NSW population aged ≥ 20 years which represented the current incidence of suicide and attempted suicide in NSW was developed in partnership with a consortium of stakeholders, subject matter experts, and consumers with lived experience. Scenarios relating to current suicide prevention initiatives were investigated to identify the combination of interventions associated with the largest reductions in the projected number of attempted suicide and suicide cases for a 5-year follow-up period (2019–2023). Results: The largest proportion of cases averted for both suicide and attempted suicide over the intervention period was associated with community-based suicide prevention outreach teams and peer-led drop-in facilities (6.8% for attempted suicide, 6.4% for suicide). A similar proportion of potential cases averted of both attempted suicide and suicide (6.4%) was evident for targeted interventions focusing only on those in the population with suicidal thoughts and a previous history of attempted suicide. Conclusion: Initiatives that are characterised by the short-term stabilisation of suicidal distress at the point of crisis, averting the need for a hospital encounter, and the referral of individuals to non-acute community-based care were associated with the largest potential reductions in suicidal behaviour in NSW.