Background: Wearable technologies offer new opportunities to address in-school physical inactivity. However, children are often excluded from discussing issues which directly impact them, including the use of wearable technologies in a school setting. Thus, the aim of this study is to understand primary school pupils' experiences and perceptions of using wearable physical activity monitoring technologies within schools. Methods: Nine semi-structured focus groups were conducted with 41 Year 5 and 6 pupils (19 girls, 22 boys) from 5 primary schools in the South West of England. Focus group transcripts were analyzed using a reflective thematic approach. Results: Pupils made valuable contributions to discussions around wearable technologies, considering both advantages and disadvantages. Most importantly, when discussing use in schools, pupils were mindful that while they wanted to see their own activity and saw benefit in teachers knowing their activity, they felt comparisons in classes could lead to negative emotions for some pupils. Conclusion: The findings from this study can contribute to a more detailed understanding of pupils' perspectives, which can help inform school-based interventions which aim to address physical inactivity and associated inequalities. Instead of using wearable devices for individual pupil ownership, schools should access data-insights with the intention of changing school practices.