Abstract Background Irritability is common in children and adolescents with Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD) and with anxiety/depressive disorders. Although youth irritability is linked with psychiatric morbidity, little is known regarding its non-pharmacological treatments. Developing non-pharmacological treatments for children with severe, chronic irritability is an important target for clinical research. To achieve this goal, we will test the benefits of parent-focused therapies in reducing irritability. The aim of the study is to compare Parent Management Training (PMT) and Non-Violent Resistance Training (NVR) programs with treatment-as-usual (TAU) on the improvement of irritability in children and adolescents with a baseline Parent-rated Affective Reactivity Index of 4 or higher, in the context of ADHD and other emotional and behavioural disorders. Additionally, we will assess (i) improvement of irritability at different times and according to different informants (parents, children, clinicians); (ii) improvement of parental strategies; and (iii) acceptability of the interventions, exploring possible mechanisms of the therapeutic effect. Methods Two hundred and seventy participants between 6 and 15 years with ADHD and other emotional and behavioural disorders will be recruited and randomly assigned with their parents to the PMT, NVR, and TAU groups. PMT and NVR programs have 10 online sessions and two booster sessions at 1 and at 3 months. The primary outcome measure is the change from baseline at 3 months after completion of the program of the Clinician-rated Affective Rating Scale (CL-ARI) assessed by a blind evaluator. Secondary outcome measures include the change from baseline from those scales: the CL-ARI, the Clinical Global Impression Improvement scale, the Parenting and Familial Adjustment Scales, the Child-rated Cranky thermometers and the Parent-rated ARI. We will assess the parent’s expressed emotions and reflexivity during the online five-minute speech sample, clinical dimensions through the Child Behavior Checklist 6–18 and the Inventory of Callous Unemotional traits. Evaluations will be done remotely at baseline and at 1- and 3-months follow-up visits. Discussion We expect a benefit in controlling irritability in the treatment groups. This will constitute an important achievement in promoting parental support programs in the treatment of irritability in the context of emotional and behavioural disorders. Clinicaltrials.gov. Number: NCT05528926. Registered on the 2nd of September, 2022.