Maintaining good level of physical fitness (PF) is important to the health of children and adolescents. Unfortunately, many countries shown that children and adolescent's PF level was declining in the past decade and this declination was found to be associated with low level of physical activity (PA). Although insufficient PA was attributed by multiple factors, prolong exposure to screen-based activities (i.e., TV viewing and video game plays) was claimed as one of the major factors. Growing body of evidence has been suggesting that Active Video Game (AVG) play may be a promising tool to reverse this physically inactive lifestyle in children and adolescents. However, before applying AVG on PA and PF interventions, a better understanding on this emerging tool is essential. The purposes of this chapter are to provide an overview regarding the rationale and efficacy of applying AVG to promote PA and PF in children and adolescents. In additional, potential challenges for AVG research are also discussed.