Background: LGBQ+ people (Lesbian, Gay, Bisexual, Queer) are at-risk of discrimination and developing mental health issues within general populations. Limited research has assessed their mental health in emergency services occupations, a population which are known to experience poorer mental health. The current study explores the extent to which sexual orientation is associated with higher rates of mental health issues among emergency personnel. Methods: A stratified random sample of employees from twenty-nine police (N = 8,088), ambulance (N = 3,473), and fire and rescue (N = 2,975) agencies from around Australia participated in a cross-sectional mental health survey (N = 14,536, male = 64.2%, 42.7% over 45 years of age, heterosexual = 92.7%). Results: Employees with a bisexual/pansexual orientation or those who were not sure about their sexual orientation were significantly more likely to report suicidal thoughts, suicide plans, psychological distress, and illicit drug use when compared with heterosexual employees. LGBQ+ employees reported significantly higher rates of lifetime suicide plans and attempts. Specifically, LGBQ+ fire and rescue personnel were roughly six times more likely to report lifetime suicide attempts, and approximately five times more likely to use illicit drugs weekly than their heterosexual colleagues in the fire and rescue sector. Female LGBQ+ personnel were significantly less likely to consume illicit drugs weekly and monthly than male LGBQ+ personnel. Conclusions: Emergency services personnel are already at-risk of developing pervasive mental health difficulties. It is important that organisations foster positive working environments, particularly for LGBQ+ people who may be more marginalized within organisations.