Dysregulated eating behaviors, comprising subthreshold and clinical binge-eating disorder (BED) and bulimia nervosa (BN), are increasing among the general population, with a consequent negative impact on one's health and well-being. Despite the severity of these outcomes, people with BED and BN often face a delay in receiving a diagnosis or treatment, often due to difficulties in accessing care. Hence, evidence-based and sustainable interventions for eating symptomatology are needed. The present study aims to assess the effectiveness of a web-based 10-session multidisciplinary group intervention based on Dialectical Behavior Therapy (DBT) for BED and BN, aimed at reducing psychological distress and binge-eating-related symptomatology in a sample of patients with dysregulated eating behaviors and including one session of nutritional therapeutic education. A total of 65 participants (84.6% F; age M = 38.5 ± 13.2; experimental group, N = 43; treatment-as-usual group, TAU, N = 22) took part in the study. The results show, after the 9 weekly sessions, a significant reduction in binge-eating-related symptomatology and general psychopathology and an increased self-esteem and eating self-efficacy in social contexts in the experimental group compared to the treatment-as-usual group (T0 vs. T1). Improvements in the experimental group were significantly maintained after one month from the end of the intervention (T2) in terms of binge-eating symptoms, general psychopathology, and eating self-efficacy in social contexts. This study supports the effectiveness of a brief web-based multidisciplinary group intervention in reducing eating symptomatology and psychological distress and enhancing self-esteem and eating self-efficacy in a group of people with dysregulated eating behaviors. Brief web-based interventions could represent an accessible and sustainable resource to address binge-eating-related symptomatology in public clinical settings.