Primary objectives were to examine: 1) changes in movement behaviours (i.e., outdoor play (OP), organized physical activity (PA), screen time (ST), sleep) across the first two years of COVID-19 among Canadian toddlers and preschoolers, and 2) intrapersonal, interpersonal, community, and policy moderators of change in movement behaviors. Participants were 341 Canadian parents of children (start of study: 1-4 years; 48% female). Participants completed online questionnaires regarding their children’s movement behaviours and intrapersonal, interpersonal, and community factors at five time-points before and throughout the pandemic (T1-T5). Data from government websites were also used for some community and policy factors. Linear mixed models were conducted. Compared to pre-COVID-19 (T1): OP was on average 30 minutes/day higher at T2 and T3, organized PA was on average 62, 44, 37 minutes/day lower at T2, T3, T4, ST was on average 67, 17, 38, 52 minutes/day higher at T2, T3, T4, T5, and sleep was on average 30, 36, 82 minutes/day lower at T3, T4, T5. Significant moderating variables were observed for OP (parental education, parental work inside home, COVID-19 restriction severity), organized PA (children’s sex, started kindergarten, non-parental care, parental education, household income, parental employment status, house type, indoor home space and support for PA), ST (non-parental care, parental marital status) and sleep (children’s T1 age group, started kindergarten, parental place of birth, parental employment status). All movement behaviors changed across the first two years of COVID-19 but patterns and moderators were behaviour-specific. Children from lower socioeconomic status families had the least optimal patterns.