Objective: Binge-eating disorder (BED) and subthreshold BED (SBED) are prevalent in adults and associated with mental health problems including depression, non-suicidal self-injury, lower quality of life, and suicidality. There is solid evidence that binge-eating behaviors are also prevalent in adolescence, but knowledge about mental health in community adolescents with BED of different frequency thresholds is more limited. We aimed to investigate the prevalence and mental health problems associated with SBED of low frequency and/or limited duration compared with BED in a Danish community sample of adolescents. Methods: We included 2509 adolescents who completed the online survey of the 16–17-year follow-up of the Copenhagen Child Cohort (CCC2000), including items on BED symptoms approximating the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria, and items on mental health and quality of life. Results: The 1-year prevalence of SBED was 2.7% (95% confidence interval [CI]: 2.0%–3.3%) with a male:female ratio of 1:3.7; comparable to previous findings on BED in the same sample. SBED was also comparable to BED concerning cross-sectional associations with overall mental health problems, lower health-related quality of life, depressive symptoms, and suicidal ideation, whereas no associations were seen with non-suicidal self-injury after Holm–Bonferroni correction. In both groups, thoughts and behaviors concerning food and weight interfered significantly with daily life. Discussion: SBED and BED were equally prevalent in this adolescent community sample, and similarly associated with indicators of poor mental health. The findings indicate that community adolescents reporting symptoms approximating clinical criteria of BED need intervention irrespectively of symptom frequency or duration. Public Significance: This study adds knowledge to the field by comparing BED of low frequency and/or limited duration (“subthreshold BED,” SBED) with full-syndrome BED in adolescents and showing that SBED in adolescence is both prevalent and associated with poor mental health to a similar extent as that of BED. Findings indicate that self-reported symptoms according to clinical criteria of SBED and BED alike constitute a public health problem and point to youngsters in need of intervention.