Introduction To examine demographic and psychosocial correlates of suicidal ideation and suicide attempts among a large cross-section of sexual orientation populations in Australia, including lesbian, gay, bisexual, pansexual, queer, and asexual (LGBQ) people. Methods A national survey was conducted involving 5,174 cisgender LGBQ participants aged 18+ years. Multivariable regressions identified factors associated with recent suicidal ideation and suicide attempts. Results In all, 37.2% reported suicidal ideation and 3.9% a suicide attempt in the past 12 months. The likelihood of suicidal ideation was greater for those who identified as queer or felt treated unfairly or socially excluded due to their sexual orientation, and lower for those in a committed relationship, who felt part of LGBTIQ communities, or felt accepted in family, work, and health services. The likelihood of suicide attempts was greater for those aged younger or had recently experienced verbal abuse or social exclusion, and lower for those in a committed relationship or who felt part of LGBTIQ communities. Limitations Participants were recruited largely through paid Facebook advertising and the sample may therefore not be representative of all LGBQ adults in Australia. However, a representative population-level study would require the collection of population demographic data to provide the necessary and sexual identity is not included in the Australian Census. Conclusion These findings highlight an urgent need for supporting LGBQ people and may help inform tailored support services, including culturally-safe suicide prevention programs. These could involve peer support, trauma-informed counselling, supporting committed relationships, and addressing marginalization in the wider community.