The aim of the current research was to evaluate the effect of a solution-focused approach on levels of self-efficacy and self-esteem in adolescents with attention-deficit/hyperactivity disorder (ADHD). A mixed design was used, where the quantitative aspect was a randomized controlled study and the qualitative aspect was a case study design. Adolescents with ADHD (N = 41) were randomized into intervention or control groups. Control groups received existing treatment in outpatient clinics, whereas interviews based on a solution-focused approach were conducted with the intervention groups. After the interventions, differences were noted between groups with time, self-efficacy, and self-esteem, with increases in self-efficacy and self-esteem. Significant differences were found between postintervention and follow-up scores. Six themes were determined in the qualitative findings. Nurses in the adolescent mental health field can use the principles and techniques of the solution-focused approach when providing care.