Deficits regulating emotions are a core process underlying both substance use and mental health disorders. Research has focused on identifying one-to-one associations between individual emotion regulation (ER) strategies and mental health symptoms. Consequently, little is known about how patterns of ER relate to a broad range of psychopathology, in treatment seeking young people. Latent class analysis was used to examine patterns of ER strategies and their relationship with symptoms of depression, anxiety, eating disorders, substance use and borderline personality disorder, in a sample of young treatment seekers. Participants were young people (N = 306, M = 20.8 years) accessing youth advocacy and support or mental health services in Australia. Participants recalled an emotionally-arousing event experienced when on their own and indicated their use of 14 possible ER responses in an online questionnaire. Symptoms of mental health and substance use were measured. The LCA identified three distinct classes of ER responses: Ruminators/avoiders (n = 76), active regulators (n = 81), and low regulators (n = 129). The ruminators/avoiders endorsed the most severe symptom picture across all disorders except alcohol use. Within this cohort, distinct patterns of ER responding had unique relationships with symptoms of psychopathology. The deleterious impact of heightened maladaptive ER strategies (rumination and avoidance) in the absence of adaptive strategies was highlighted.