Background: Contextual factors are likely to influence whether young children are able to adhere to recommended health behaviours. This study aimed to: (1) describe the social and environmental characteristics of children under five living in Soweto, South Africa; and (2) determine factors associated with screen time and outdoor play in this population. Methods: Household surveys were conducted in Soweto to collect data on children's screen time and access to outdoor space, as well as information about the household. A multilevel regression analysis was conducted for each outcome. Results: Data on 2309 children aged five or under were included in this analysis. Children used screens for an average of one and a half hours per day during the week, and nearly 2 hours per day on weekends. Almost all (92%) children had a safe space to play inside, while just over a third (34%) had a safe space to play outside. A higher socioeconomic status was associated with less time spent playing outside and more screen time. Conclusion: Interventions promoting outdoor play and restricting screen time are essential for improving health trajectories, but need to address structural barriers that exist, in order to protect the safety of children while promoting health behaviours.