Objective: The association between chemical dependency and Attention-Deficit Hyperactivity Disorder is widely recognized, but there is less data regarding modern behavioral addictions among young adults. Method: In this cross-sectional study, a sample of 408 Hungarian college students (67.2% female, mean age 23.37 years [SD = 3.87]) responded to an online survey including the Adult ADHD Self-Report Scale, the Center for Epidemiologic Studies-Depression Scale (CES-D), the Procrastination Scale, the Short College Boredom Scale, and the Smartphone Addiction Scale (SAS-SV). Results: Regression analyses showed that passive procrastination (ß = .31, p < .001), depression (ß = .20, p < .001), academic boredom (ß = .18, p < .001), active procrastination (ß = −.12, p < .001), and smartphone addiction (ß = .13, p < .001) were significantly related to ADHD symptoms, accounting for 41% of the variance. Conclusion: Findings provide important additions to knowledge of mental health challenges among young adults with ADHD.