There is a lack of evidence regarding 24-hour movement behaviors of young children from low- and middle-income countries. This study examined Mongolian preschoolers' adherence to the World Health Organization's guidelines for physical activity, sedentary behavior, and sleep; their associations with health indicators, and the feasibility of the SUNRISE International study in Mongolia. Preschool-aged children were recruited from 5 kindergartens in urban and rural areas of Ulaanbaatar city and Tuv province in Mongolia. Physical activity and sedentary behavior were measured by an ActiGraph accelerometer worn for 5 consecutive days. Screen time and sleep were reported by parents. The National Institute of Health and Early Years Toolboxes were used to assess motor skills and executive function, respectively. One hundred and one children participated in the study (mean age = 4.82y, boys = 58), with 88% (n = 89) having complete data for analysis. The proportion of children who met the recommendations for physical activity, sedentary screen time, and sleep was 61%, 23%, and 82%, respectively. Only 7% met all recommendations. Meeting the sleep recommendation individually (P = .032) and in combination with the physical activity recommendation was associated with better gross (P = .019) and fine (P = .042) motor skills. Spending more time in physical activity was positively correlated with motor development. Results confirmed that the SUNRISE study protocol was feasible, age-appropriate, and enjoyable for children. The results of the SUNRISE pilot study will help inform the SUNRISE Mongolia main study and lay the groundwork for future research into children's 24-hour movement behaviors in Mongolia.