The Prime Minister says New Zealand has been asked to participate in next year's G20 meetings during Australia's year as chair.
New Zealand is not a member of the group because it is too small, and this will be the first time it has been invited to contribute to a full year's deliberations.
The host of the annual G20 meeting is able to invite additional countries it thinks will add value during its year as chair.
John Key says the Australian Prime Minister, Tony Abbott, phoned him on Thursday to extend the invitation.
He says as a small trading nation, New Zealand has a significant stake in the global economy and it will provide valuable input.
Mr Key says it will bring some 'small economy' perspectives to the discussions, which may be somewhat different from the issues facing major economies.
The G20 grouping includes Argentina, Australia, Brazil, Canada, China, France, Germany, Indonesia, India, Italy, Japan, Republic of Korea, Mexico, Russia, Saudi Arabia, South Africa, Turkey, United Kingdom, United States, European Union.