The reforms also included plans to address an alleged culture of bullying within some fire brigades - described by the minister today as the elephant in the room.
In a speech in Wellington, Mr Dunne said the new national service was not a takeover by the Beehive or by Fire Service headquarters, but a "merging of the talents".
The changes stemmed from a 2013 review, which found that fire services had no legal mandate for their expanded role which included search and rescue and motor vehicle extrications.
A further Government-led review this year underlined the need for changes to the service, in particular more support for volunteers, making sure fire services met community expectations, and modernising the service to make it fit for the 21st century.
Mr Dunne said the single, integrated national fire service would recognise and respect the differences between the various parts of the sector.
In order to maintain a strong regional voice, a series of regional committees would be set up. The new national body would be responsible for resourcing fire services, training and professional standards, but would work with the regional committees on "delivery matters".
Mr Dunne promised that the new investment in volunteers would not affect the paid workforce.
He also said he was committed to ensuring the service had an appropriate level of funding for equipment, training, back-up and support.
On the issue of bullying, the minister said the new organisation would be tasked with ensuring all staff worked more effectively together.
Over the last two years, various reports of intimidation and unfair dismissal have emerged at several brigades across the country.
New proposals for dispute resolution were being developed and would be confirmed early next year.
A new organisation along the lines of the Fire Service Commission would be developed to manage the transition to a single national service, and it would combine the Fire Service, the Rural Fire Service, various rural branches and the enlarged rural fire districts (ERFDs).
Legislation to enact the reforms would be introduced next year, and the changes were expected to be in place by mid-2017.
Mr Dunne said: "Taken together, these changes represent not only the biggest reform of our fire service since the aftermath of the disastrous Ballantyne's fire ... but they will also help position them well for the future and ensure both community accountability and service sustainability".
