Clavicle fractures in children are common and usually go on to achieve solid union with closed treatment. A limited number of pediatric clavicle fracture nonunion cases have been reported in the literature, none of which were directly associated with hypovitaminosis D. We report the youngest case to our knowledge in a 4-year-old vitamin D-deficient male with a 6-month-old right midshaft clavicle fracture nonunion that was treated successfully with vitamin D supplementation, followed by open reduction and internal fixation with autologus iliac crest bone grafting.