Background Attention deficit hyperactivity disorder (ADHD) is frequently associated with emotional dysregulation (ED). ED is characterized by excessive and inappropriate emotional reactions compared to social norms, uncontrolled and rapid shifts in emotion, and attention focused on emotional stimuli. Few studies have evaluated non-pharmacological interventions to improve ED in children with ADHD. The current randomized controlled trial assesses the efficacy of a cognitive behavioral therapy (CBT) intervention compared with a theater-based intervention (TBI) in children with ADHD and ED. Methods Sixty-eight 7- to 13-year-old children with ADHD and ED will be recruited and randomly assigned to the CBT or TBI group. CBT aims to reduce ED by teaching anger management strategies. TBI seeks to reduce ED by improving emotion understanding and expression through mimics and movement. In both groups, children participate in 15 1-h sessions, and parents participate in 8 sessions of a parent management program. The primary outcome measure is the change in the “Aggression” sub-score of the Child Behavior Checklist (CBCL). Secondary outcome measures include overall impairment (Children’s Global Assessment Scale, Strengths and Difficulties Questionnaire), personality profile (Hierarchical Personality Inventory for Children), executive function (Behavioral Rating Inventory of Executive Function), quality of life (Kidscreen-27), parental stress (Parenting Stress Index, 4th edition), parental depression (Beck Depression Inventory-II), and impact of child disorders on the quality of the family life (Parental Quality of Life and Developmental Disorder). Discussion Children with ADHD and ED are at risk of functional impairment and poor outcomes and have specific therapeutic needs. This randomized controlled trial wants to assess non-pharmacological treatment options for this population. Trial registration Clinicaltrials.gov. NCT03176108. Registered on June 5, 2017.