Background Malunited proximal radius fractures causing dislocation of the radio-capitellar joint are rare. We present a case of a two-year-old female patient with such an injury who was treated with a proximal radius osteotomy with good long-term outcomes. Method/results Case study of a single patient with a malunited proximal radius fracture which was identified as causing radio-capitellar dislocation who underwent corrective osteotomy with a good result. Conclusion Our opinion is that a corrective osteotomy for a malunited proximal radius fracture causing radio-capitellar dislocation is a sound treatment option and that no supplementary soft tissue reconstruction such as annular ligament exploration/reconstruction is necessary.