Preschoolers are not meeting physical activity recommendations and are spending an extensive amount of their day sedentary. Interventions targeting teacher-led strategies can benefit children's physical activity levels the most. The purpose of this feasibility study was to examine the effects of an indoor teacher-guided and -led preschool physical activity intervention in low-income schools. Sixty-six preschoolers and twelve preschool teachers participated in this study. Intact classrooms were randomly assigned to either an intervention or control group. A 2 x 3 mixed ANOVA was used to test changes by group and time. Follow-up measurements included Post-hoc analysis. There was a significant group by time interaction in children's moderate-to-vigorous physical activity (MVPA) levels during indoor time (p = 0.036) and a significant effect on time in children's MVPA levels during outdoor time (p = 0.002). Teacher's identified that when planned, physical activity opportunities are easy to implement during indoor time. Moreover, teachers indicated that they enjoyed providing physical activity opportunities into the classroom setting and the children enjoyed participating in the activities implemented. Teachers identified implementation barriers could be correlated with decreased levels of children's physical activity. Our findings show that a teacher-guided and -led indoor preschool physical activity intervention is a feasible approach that can acutely increase children's MVPA levels.