Background: Engaging in classroom-based physical activity (PA) breaks may help increase children's subjective wellbeing and enjoyment of PA, important precursors for children to remain engaged in PA. We conducted a systematic review to investigate the effect of brief classroom-based PA interventions on primary school children's subjective wellbeing and enjoyment of PA. Methods: Databases were reviewed between the earliest date of records and April 2020. Eligibility criteria included peer-reviewed empirical quantitative or mixed methods studies reporting enjoyment of PA or wellbeing outcomes of participating in a brief classroom-based PA program. Fifteen papers were included. Interventions supported 7022 child participants enrolled at baseline and 6286 children analyzed in interventions across 148 schools. Results: Thirteen studies examined the effect of brief classroom-based PA interventions on subjective wellbeing. Four found a significant positive effect for children in the intervention group (specifically for children's self-efficacy in learning with video exercises, quality of life, and self-confidence). Eight studies examined the effect of brief classroom-based PA interventions on enjoyment of PA. Five studies reported a positive effect for children in the intervention group and only 1 study found a negative effect for 1 grade level of children in the intervention group. The remaining studies with wellbeing and/or enjoyment outcomes reported no significant effect. Conclusions: Findings from these studies indicate that the integration of brief PA breaks may support PA enjoyment and specific self-beliefs and quality of life perceptions that contribute to children's subjective wellbeing. However, more research is needed to confirm this effect.