Air New Zealand and United Airlines have entered into a revenue sharing agreement.
Under the deal the airlines will work together to promote and sell both airlines' services between New Zealand and the mainland United States, including domestic feeder services in both New Zealand and the United State.
The revenue sharing deal is similar to that Air New Zealand has with Virgin Australia, Cathay Pacific, Singapore Airlines and Air China.
United Airlines will begin services from San Francisco to Auckland service on July 1.
Air New Zealand and United have worked together since 2001 coordinating closely on codesharing, frequent flyer programmes and distribution.
The revenue share agreement will deepen this cooperation, the airlines say.
Subject to United Airlines obtaining government approval, it will begin operating a three-times-weekly Boeing 787-8 Dreamliner service between San Francisco and Auckland in July, moving to daily services operated by a larger 787-9 aircraft in November.
Air New Zealand chief executive Christopher Luxon said both the airline and New Zealand's economy stand to benefit significantly from the alliance.
"The United States is New Zealand's third largest tourism source market, contributing almost a billion dollars to our economy in the past financial year," he said.
"We know this is just the tip of the iceberg though, with around 30 million Americans actively considering New Zealand as a holiday destination."
United Airlines vice chairman and chief revenue officer Jim Compton said United was very excited about its agreement.
"Together, United and Air New Zealand will offer customers more seamless connections between New Zealand and cities across the U.S. than any of our competitors."
Air New Zealand currently operates direct to five North American cities with daily services from Auckland to San Francisco, double daily services to Los Angeles, four services per week to Vancouver and Honolulu, and five services per week from Auckland to Houston, increasing to daily flights during the December/January peak period.
Once United begins operating its Auckland-San Francisco flights the airlines will operate complementary services on the route, with United's flights arriving into San Francisco in the early morning and Air New Zealand's flights arriving around midday.
United Airlines and United Express operate an average of nearly 5000 flights a day to 342 airports across six continents.
In 2015, United and United Express operated nearly two million flights carrying 140 million customers.
Rival carrier American Airlines will start services in competition from Los Angeles to Auckland in June.