United now has a total of 22 Dreamliners in its fleet and expects to take delivery of three more this year.
The airline this month apologised for problems following its merger with Continental, and said it planned to start services to Auckland from July next year.
United plans to build up to daily services between New Zealand and the US as part of a growing partnership with its Star Alliance ally, Air New Zealand. The airlines plan to move to a revenue-sharing deal.
United last flew into Auckland Airport in 2003 and the airport company said the additional 140,000 seats every year would contribute $190 million to the economy.
Flight Centre managing director Chris Greive said more capacity should lead to better fares.
The deal between Air New Zealand and United has been seen as a way of blocking a possible entry into the Auckland-US market by the rival Qantas-American Airlines alliance.
Greive said, however, that there seemed to be room for another carrier on the route and there were still rumours of American entering the market. The United States is this country's third-largest international visitor market, after Australia and China. In the year to August 2015, 236,272 Americans visited New Zealand, an 11.2 per cent increase on the previous year, and approximately 80 per cent of them arrived at Auckland Airport.
"The new United Airlines service will improve our air connectivity to North America. It provides greater airline choice for both the growing numbers of American visitors coming to New Zealand, particularly from beyond United Airlines' San Francisco hub, and the increasing number of New Zealanders travelling to the United States," said Norris Carter, Auckland Airport's general manager for aeronautical commercial.
Last month United's new chief executive, Oscar Munoz, said in full-page newspaper adverts the merger with Continental had failed to live up to the expectations of both flyers and United staff. Since the merger five years ago, United has been plagued with chronic delays, computer outages and dissatisfied workers.
Flying high
• United Airlines and its regional airline United Express operate an average of nearly 5000 flights a day to 362 airports across six continents.
• Last year the airlines operated nearly two million flights carrying 138 million customers.
- additional reporting AP
