More than a third of Air NZ seats expected to be filled by Australians, who lost a direct service in April.
Air New Zealand's flights to Buenos Aires will be more than a third filled with passengers from Australia, an analysis of the service says.
Capa Centre for Aviation says the "bold" move into Latin America next December has been made possible by a new partnership with Aerolineas Argentinas, which will provide connections within South America and local sales support.
"For Air New Zealand, Buenos Aires fills the last major white spot in its network following the upcoming resumption of services to Singapore.
"Argentina has proven to be a challenging market for foreign carriers but for Air NZ it represents the best South American option with a risk level that is acceptable with the right partnerships," Capa says.
Aerolineas pulled out of this region in April, ending a Buenos Aires-Sydney direct service hit by high fuel costs and limitations of an aircraft at the edge of its its range. The airline pulled out of its service to Auckland in 2012.
Air NZ sees potential to build local NZ-Argentina traffic as more Kiwis holiday in South America, hopefully using Buenos Aires as a jumping off point, and as economic ties grow.
Latin America is also seen as a potential growth market for inbound tourism with Tourism New Zealand expanding its presence in Brazil as part of a $44.5 million push into attracting visitors from emerging growth markets. Brazil has extensive air links to Chile.
Capa said Air New Zealand recognised the NZ-Argentina market was limited and plans to rely heavily on sixth freedom traffic, particularly to and from Australia.
Chief executive Christopher Luxon told a Star Alliance meeting in Delhi about 35 per cent of traffic for the Auckland-Buenos Aires route would come from Australia, which has a large Argentine community.
Aerolineas' withdrawal from the Australian market has left Qantas and oneworld partner LAN as essentially the only option between Australia and Argentina. Qantas and LAN are the only carriers with non-stop flights between Australia/NZ and Latin America.
A long-running Facebook page "Why Air NZ should fly to South America" has posts complaining about high fares on the route and travel agents have said the entry of Air New Zealand into the region should bring down prices.
Luxon also said he expected connections to and from Asia to initially account for about 10 per cent of traffic on Auckland-Buenos Aires.
The service, which has yet to get regulatory approval, would be operated with a refurbished Boeing 777-200 aircraft's three return flights a week starting in December 2015.