Objective: The authors used a population-representative sample and health administrative data to quantify suicide-related behavior leading to acute care or deaths across self-identified heterosexual, gay/lesbian, and bisexual individuals. Methods: Data from a population-based survey (N=123,995) were linked to health administrative data (2002-2019), and differences in time to suicide-related behavior events across sexual orientations were examined using Cox proportional hazards regression. Results: The crude incidence rates of suicide-related behavior events per 100,000 person-years were 224.7 for heterosexuals, 664.7 for gay/lesbian individuals, and 5,911.9 for bisexual individuals. In fully adjusted (gender-combined) models, bisexual individuals were 2.98 times (95% CI=2.08-4.27) more likely to have an event, and gay men and lesbians 2.10 times (95% CI=1.18-3.71) more likely, compared with heterosexual individuals. Conclusions: In a large population-based sample of Ontario residents, using clinically relevant outcomes, the study found gay/lesbian and bisexual individuals to be at elevated risk of suicide-related behavior events. Increased education among psychiatric professionals is needed to improve awareness of and sensitivity to the elevated risk of suicide-related behavior among sexual minority individuals, and further research on interventions is needed to reduce such behaviors.