The purpose of this study was to examine the associations between fundamental motor skills (FMS; including locomotor and object-control skills), moderate-to-vigorous physical activity (MVPA), and sedentary behavior among young Hispanic and non-Hispanic children. Using the prospective research design spanning one academic school year, we recruited 671 children (6.96 ± 1.6 years, 46% girls) from four primary schools in North Texas, 300 of whom were Hispanic and 371 non-Hispanic children, with 90% of the Hispanic and 74% of the non-Hispanic children from low-income families. All participants completed the PE Metrics™ FMS assessment and wore Actical accelerometers. Hispanic children demonstrated a lower level of MVPA on school days than their non-Hispanic peers. After adjusting for sociodemographic variables, both locomotor and object-control skills significantly predicted school-based MVPA for the non-Hispanic groups, while only object-control skills significantly predicted MVPA for the Hispanic group. For both ethnic groups, locomotor skills significantly predicted school-based sedentary behavior. The findings shed light on future motor competence–based interventions for physical activity promotion and obesity prevention among young Hispanic as well as non-Hispanic children.