Mental health disparities have been documented among lesbian, gay, and bisexual (LGB) adults in the United States. Substance use disorders and suicidal ideation have been identified as important health concerns for this population. However, the interrelationships among these factors are not well understood. This study aims to investigate the interrelationships among mental health, substance use disorders, and suicidal ideation among LGB adults in the United States using a population-based statewide survey. Our study was an observational cross-sectional analysis, and the data for this study were collected from a sample of LGB adults who participated in the statewide survey. The survey collected information on mental health, substance use disorders, and suicidal ideation using validated measures. Descriptive statistics and inferential data analysis were conducted to explore the interrelationships among these factors. The results showed that LGB adults who reported higher levels of depression and drug abuse and dependence also reported higher levels of suicidal tendency and mental illness. Inferential data analysis using χ2 tests revealed significant differences in depression score (χ22=458.241; P<.001), drug abuse and dependence score (χ22=226.946; P<.001), suicidal tendency score (χ22=67.795; P<.001), and mental illness score (χ22=363.722; P<.001) among the 3 sexual identity groups. Inferential data analysis showed significant associations between sexual identity and mental health outcomes, with bisexual individuals reporting the highest levels of depression, drug abuse and dependence, suicidal tendency, and mental illness. This study provides important insights into the interrelationships among mental health, substance use disorders, and suicidal ideation among LGB adults in the United States. The findings underscore the need for targeted interventions and research aimed at addressing the mental health needs of sexual minority populations. Future research should aim to better understand the underlying mechanisms driving these disparities and develop culturally sensitive and tailored interventions that meet the unique needs of LGB individuals. Reducing stigma and discrimination against sexual minority populations is also crucial to improving their mental health outcomes.