Background: Energy drinks are predominantly targeted to young adult consumers; however, there has been limited research into their effects on psychological functioning in this demographic group. This study examined cross-sectional associations between energy drink consumption and mental health in a population-based sample of young adults participating in the Western Australian Pregnancy Cohort (Raine) Study. Methods: We used self-report questionnaires to assess energy drink consumption and mental health (Depression Anxiety Stress Scale-21; DASS-21) at the 20-year cohort follow-up. In the regression analyses, we considered associations between energy drink consumption (mL/day) and continuous DASS-21 scores, adjusting for sociodemographic variables, alcohol and drug use, physical activity, body mass index (BMI), and dietary intake. Our sample included 502 males and 567 females (mean age 20 ± 3 years).Results: After adjusting for potential confounding factors and controlling for coexisting mental health problems, energy drink consumption (per 100 mL/day) was significantly associated with anxiety (but not depression or stress), and this relationship was found only in males (β = 0.32; 95% CI = 0.05, 0.58). Conclusions: Our study found that energy drink consumption was associated with increased anxiety in young adult males. Further research into the possible contribution of energy drink use to the development of mental health problems in young adults is needed.