Body image and self-perception are highly related to psychological health and social well-being throughout the lifespan. Body image problems can lead to pathologies affecting the quality of life. Thus, it is essential to analyse perceived self-image from an early stage. This study aimed to assess body image and dissatisfaction in preschoolers, analyzing possible differences depending on sex (boy/girl) and school location (rural/urban). The sample consisted of 304 preschoolers from Extremadura (Spain) between three and six years of age. The Mann–Whitney U test was used to evaluate the differences in scores according to sex and centre location. The results showed significant differences in the body shape perception depending on the student’s sex, with females showing higher scores in their Body Mass Index (BMI). However, females showed greater body dissatisfaction than their male counterparts, with greater disagreement between their perceived and desired figures. Actions and programmes to promote children’s healthy body image need to be implemented with consideration for differences between the sexes.