Former Defence chief Jerry Mateparae will stay on as head of the Government Communications Security Bureau until June, then become the next Governor-General in August.

He will be knighted - by the Queen herself if tradition is followed - and will begin his five-year term when Sir Anand Satyanand steps down.

He will be 56 when he becomes New Zealand's 20th Governor-General and Prime Minister John Key said yesterday that his relatively young age was a factor in choosing him.

"I just think we are a young, modern country. It's a great fit for what we are doing," he said. Mr Key said he had compiled a list but General Mateparae was his first choice.

He had taken advice from the State Services Commission to see if there would be any conflict of interest in remaining in his new post for a few months and was assured there was not.

General Mateparae began his job as director of the GCSB in February after a distinguished 38-year career with the armed forces, including five years as chief of the Defence Force.

The GCSB provides the Government with foreign intelligence and the director is accountable to the PM.

General Mateparae's appointment was greeted with wide approval and Mr Key revealed he had consulted Opposition Leader Phil Goff several weeks ago.

Mr Key had also phoned the Queen and "she was thrilled".

General Mateparae said when Mr Key called him up to his office a few weeks ago, he thought it was to talk about the GCSB.

"You cannot imagine my surprise when he asked me to be New Zealand's next Governor-General."

After mulling it over for a couple of days with his wife, Janine, he decided it was an opportunity not to miss.

"The more I have thought about the role of Governor-General, the more confident I've felt that I could develop some of the things that I've been interested in, that I've seen as important: the notion of service to others, the drive for excellence and harnessing the strengths of young New Zealanders."

General Mateparae was the first Maori to head the Defence Force but he will not be the first Maori Governor-General. Sir Paul Reeves takes that honour and was also younger, appointed at aged 53.

General Mateparae has five children, three grown and two teenage boys still at home.

"As most parents of teenage boys will know, the boys will keep me well and truly grounded."

General Mateparae enlisted in the Army as a private in 1972.

He was born in Wanganui in 1954, and went to state schools there, Castlecliff, Rutherford Intermediate and Wanganui High School.

His tribal affiliations are to Ngati Tuwharetoa and Ngati Kahungunu.

General Mateparae said: "I have an unshakeable belief in New Zealanders. There is a Kiwi spirit that gets things done with humour, ingenuity, practicality and without bias. I've seen that spirit shine through in many New Zealanders who have served in our Defence Force, often in difficult circumstances."

He said he had seen that spirit in the aftermath of the earthquake, which had brought out the best in Cantabrians and all New Zealanders.

"The compassion and generosity that have characterised the community's response to the earthquake are a lesson and an inspiration to us all."