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."
Ms Tolley announced last month that the present Child, Youth and Family service would be replaced with a larger department for vulnerable children with a $1.3 billion annual budget to buy extra education, health, employment and social services for the families of about 230,000 "vulnerable" children -- about one in every five children.
The changes will include raising the age at which young people leave state care from 17 to 18 and reviewing a similar lift in the age of adult criminal responsibility. At present the Youth Court deals with offenders aged 14 to 16.
A new advocacy service will be set up for children and young people in state care, which will change the current role of the Children's Commissioner to monitor the state care and protection system.
Dr Wills, who served half-time while working the other half of each week as a paediatrician in Hawkes Bay, made reducing child poverty the main focus of his term in office. He did not seek a second term for personal reasons.