High quality educational settings play a crucial role in preparing a child to enter kindergarten, but little work has explored how outdoor play and complex physical activity outside school and childcare settings promote school readiness among preschoolers. To address this gap, the present study explored connections among school readiness with outdoor play and participation in complex physical activity. Parents (N = 107) reported the extent and frequency of time their child spent in outdoor play during a typical week, and what complex activities (e.g., soccer, biking, basketball) the child played over the last year. School readiness was assessed with parent reports on the Preschool Behavior and Emotional Rating Scale. Results showed participating in complex activities significantly moderated the relationship between time in outdoor play with school readiness, with time in outdoor play positively related to school readiness for children who participated in two or less complex activities. For children who participated in three complex activities, time in outdoor play was not related to school readiness. Findings offer support that encouraging both outdoor play and participation in complex physical activities could promote school readiness, particularly when opportunities for outdoor playtime are limited.