Young children’s digital media use and physical activity have gained attention in recent research. Parental co-participation has a major impact on children’s health consequences. This study addressed a gap in the research by investigating daily parental co-participation in children’s digital media use and physical play, using the family ecological model theoretical framework. The participants in this nationally representative cross-sectional study were 2512 Finnish parents with two- to six-year-old children. Parents completed a questionnaire. Sociodemographic correlates of co-participation and of the awareness of guidelines regarding co-participation and correlation between co-participation in digital media use and physical play were analysed. Parental co-participation in physical play and digital media use correlated positively. Lower parental age, male parental gender, Finnish and Swedish languages, a fewer number of children, and a male child gender were associated with more co-participation in one or both activities, and parental female gender and low family income were associated with more awareness. The awareness of guidelines was not associated with co-participation in digital media use. There were sociodemographic differences in parental co-participation. From a health counselling perspective, parents may benefit from national recommendations on digital media use and physical activity, but adherence to guidelines depends on the family context.