This cross-sectional study examined fundamental movement skill competency among deprived preschool children in Northwest England and explored sex differences. A total of 168 preschool children (ages 3–5 yr.) were included in the study. Twelve skills were assessed using the Children's Activity and Movement in Preschool Motor Skills Protocol and video analysis. Sex differences were explored at the subtest, skill, and component levels. Overall competence was found to be low among both sexes, although it was higher for locomotor skills than for object-control skills. Similar patterns were observed at the component level. Boys had significantly better object-control skills than girls, with greater competence observed for the kick and overarm throw, while girls were more competent at the run, hop, and gallop. The findings of low competency suggest that developmentally appropriate interventions should be implemented in preschool settings to promote movement skills, with targeted activities for boys and girls.