Background Suicide and homelessness share many of the same risk factors, but there is little understanding of how they are related to each other. Methods Data on 36 155 US adults (3101 veterans and 33 024 non-veterans) in the National Epidemiological Survey of Alcohol and Related Conditions-III were analysed to examine the association between lifetime homelessness and suicide, net of other factors, in a nationally representative US sample. Results US veterans with homeless histories were 7.8 times more likely to have attempted suicide than veterans with no homeless histories (24.5% vs 2.8%). Non-veterans with homeless histories were 4.1 times more likely to have attempted suicide than those with no homeless histories (23.1% vs 4.5%). Lifetime homelessness was independently associated with lifetime suicide attempts in veterans (AOR= 3.75, 95% CI 3.72 to 3.77) and non-veterans (AOR= 1.83, 95% CI 1.83 to 1.84). Conclusion The findings suggest a unique link between homelessness and suicide, especially among US veterans. Strategies to synergise homeless and suicide prevention services, particularly in the Veterans Health Administration, may benefit high-risk individuals.