Anxiety is a common issue in children and there is a need for evidence-based treatments. High levels of anxiety can profoundly hinder a child’s development and lead to impaired social skills, lower self-esteem and poorer academic achievement. The current study was the first to evaluate the effectiveness of Pause Breathe Smile - a mindfulness-based programme - for reducing anxiety symptoms and improving familial relationships in a sample of children with moderate anxiety. Pause Breathe Smile consists of eight, one-hour sessions that aim to teach children how to develop self-awareness, regulate emotions, and interact positively with others. Originally designed as a school-based intervention, the programme was adapted into a group therapy that children attended with a parent. Participants were eleven self-referred parent-child dyads. Psychological questionnaires and semi-structured interviews were used to evaluate the Pause Breathe Smile programme. Paired t-tests, modified Brinley plots with reliable changes indices, and thematic analysis were used to analyse data. Quantitative results showed children generally experienced a reduction of anxiety symptoms and improvement in emotional literacy. Evidence of enhanced familial relationships was found; children generally perceived their parent as becoming calmer and more emotionally responsive. Thematic analysis of interview data indicated children and parents worked synergistically to practise skills and benefit from the programme, which demonstrated the value of parental involvement. Both parents and children reported improved sleep, focus, emotional regulation and relational skills as benefits of the programme. Overall, the study found Pause Breathe Smile to be an effective treatment for children identified as moderately anxious, and a means of strengthening parent-child relationships.