Background Mindfulness‐based interventions improve a variety of clinical outcomes. Executive functioning (EF) and emotion dysregulation are among the proposed transdiagnostic mechanisms that such interventions are proposed to target. The aim of the current study was to evaluate the impact of mindfulness meditation training on EF and emotion dysregulation in a sample of female adolescents with elevations in attention‐deficit/hyperactivity disorder (ADHD) symptoms against a waitlist control condition. Method This study adopted a mixed 2 (treatment group, waitlist control group) × 2 (pre‐test, post‐test) design. Adolescent females (13–15 years old) exhibiting elevations in ADHD symptoms according to multiple informants were randomly assigned to a mindfulness treatment group (n = 15) or a waitlist control group (n = 15). Results Among EF laboratory tasks, planning and inhibition were higher in the treatment group relative to the control group with large effect sizes at post‐treatment. The treatment group also exhibited lower scores in self‐reported emotion dysregulation (total, nonacceptance of emotional responses, and impulse control difficulties) in comparison to the waitlist control group with large effect sizes at post‐treatment. Within group pre‐test and post‐test comparisons indicated improvement on particular facets of EF and emotion dysregulation only for the treatment group. Conclusions Mindfulness meditation training improved particular facets of EF and emotion dysregulation in adolescent females with elevations in ADHD symptoms. Treatment development efforts should target clinical populations that exhibit difficulties in these transdiagnostic mechanisms.