Principal Youth Court Judge Andrew Becroft has been appointed the country's next Children's Commissioner with a brief to monitor massive changes to Child, Youth and Family.
He will replace paediatrician Dr Russell Wills, whose five-year term ends in July.
Social Development Minister Anne Tolley said Judge Becroft would be seconded from his duties as a judge for an unusually short two-year term as Children's Commissioner.
"His input will be invaluable as we transform our care and protection system through the radical changes I recently announced, to focus on the short and long-term well-being of our children through to adulthood," she said.
"Judge Becroft's experience of dealing with troubled and at-risk young people will be vital in the development of a youth justice service aimed at preventing offending and reoffending as part of the major overhaul. His opinions will also be important as we investigate raising the youth justice age to include 17-year-olds."