Motor imagery provides a unique window on the integrity of movement representation. How this ability unfolds during development remains unknown, however. It was the aim of this cross-sectional study to chart the development of movement imagery over childhood using validated measures, and to examine its relationship to movement skill. A sample of 58 children aged 7-12 years were recruited from Australian primary schools. Motor imagery ability was assessed using the Radial Pointing Task and a (mental) Hand Rotation Task, whereas visual (or object-related) imagery was measured on a Letter Rotation Task. Motor skill was assessed on the McCarron Assessment of Neuromuscular Development (MAND). Results showed clear age differences on all measures: motor skill, motor imagery, and visual imagery. The relationship between motor imagery and motor skill was shown to become stronger with age, whereas no relationship between visual imagery and motor skill was evident at any age. Taken together, these results show that motor imagery has a distinct developmental trajectory that is entwined with the development of movement skill in children. We argue that movement imagery reflects the unfolding of internal modeling processes providing the foundation for adaptive, goal-directed movements.