Progressive lengthening using an external fixator has only recently been applied to the phalanges of the hand. A number of technical challenges exist, especially in pediatric cases, such as the size of the bone involved, the existence of the physis, and the risk of infection and neurovascular compromise. Here, we report a case of lengthening of a short distal phalanx following osteomyelitis in a 7-year-old child with a uniplanar mini-external fixator. Elongation of 63% was obtained, reaching 80% of the contralateral phalanx, with complete resolution of the preoperative functional impairment, and an acceptable cosmetic result for the patient. A mild limitation of the distal interphalangeal joint flexion as well as mild effort-related discomfort was still present at the last follow-up. No complications were recorded. Gradual lengthening of the phalanges using uniplanar minifixators can be performed safely in children with good results as long as appropriate indications and technical limitations are respected.