Background: Increased physical inactivity and sedentary behavior among children are a global health concern. Purpose: Examine associations between parents’ perceived neighborhood environment and children’s physical activity, outside time, and screen time, and whether these associations were moderated by age and socioeconomic position (SEP). Methods: Parents (N = 1212) completed a survey during the Recording and EValuating Activity in a Modified Park study. The neighborhood perceptions (social and physical environment), children’s age, physical activity, outside time, and screen time were parent-reported. The SEP was derived from the Index of Relative Socio-economic Advantage and Disadvantage. Multiple linear and logistic regressions were performed with age and SEP interactions. Results: Favorable perceptions of opportunities to be active and exercise were associated with a higher likelihood of meeting physical activity guidelines. Favorable perceptions of neighborhood ease for walking and a larger social network were also associated with more outdoor time. Moderation analyses revealed that favorable perceptions of several physical and social neighborhood environment features were associated with a higher likelihood of meeting physical activity guidelines in the high-SEP group and were negatively associated with preschoolers’ weekday screen time. Conclusion: Future neighborhood environment initiatives and interventions aiming to promote active living communities should consider differences in age and SEP.