Background: The factors associated with preschool-aged children's physical activity (PA) remains unclear. The aim of this cross-sectional study was to examine how different factors were associated with preschool-aged children's objectively measured PA and sedentary time. Methods: The study population was 5-6-year-old children (n = 140) and their parents (n = 138) from the STEPS Study in Turku in Southwest Finland in 2013-2014. PA and sedentary time were measured objectively by accelerometers from children and parents and body mass index with Tanita scale. Other factors (siblings, day care, organized PA and parents' education) were collected with questionnaires. Linear models were conducted. Results: Child's PA was positively associated with mother's PA and day care attendance. Child's sedentary time was positively associated with mother's sedentary time. Father's PA and sedentary time were associated with respective variables in children, but only among fathers with high education. Conclusion: Parental role modelling is essential in developing child's physically active and less sedentary lifestyle.