© 2020 Elsevier Inc. Considering the convincing evidence that executive functions predict academic achievement significantly, strategies to foster executive functions in the early school years are highly requested. Besides traditional cognitive training, combined physical and cognitive interventions are intended to be a feasible way of enhancing both children's daily physical activity and executive functions. The purpose of the present study was therefore to test the effectiveness of a six-week combined physical-cognitive intervention, and to compare it to both a sedentary cognitive intervention and a waitlist control group. Using a between-subjects experimental design, 189 children aged between four and six years (M = 5.34, SD = 0.59) were recruited from 14 kindergarten classes, which were randomly assigned to one of three experimental conditions: (a) combined physical and cognitive training, (b) sedentary cognitive training or (c) waitlist control group. Before and after the interventions, all three core executive functions of updating, inhibition and shifting were measured. Physical activity was objectively measured using accelerometers during one intervention session. Linear mixed models revealed that children from both the combined physical-cognitive and the sedentary cognitive intervention improved their updating performance compared to the children of the control group. Inhibition and shifting remained unaffected by both interventions. With respect to children's daily physical activity, linear mixed models showed that only the combined physical-cognitive intervention could significantly increase the amount of step counts. The results underline the feasibility of combined physical-cognitive interventions to enhance children's daily physical activity and their cognitive performance.