Cathay Pacific will be the first airline to bring the Airbus A350-1000 to New Zealand.
The airline will use what is one of the world's most advanced aircraft on its route to Auckland from December, and increase its flights to Christchurch from November 2019.
The Hong Kong-based carrier currently flies the smaller A350-900 to New Zealand and the deployment of the later model 1000 was tipped by the Herald late last year.
The largest variant, the A350-1000 for the Auckland route will carry a total of 334 passengers across its business, premium economy and economy-class cabins, 54 more passengers than the airline's A350-900 aircraft which currently serve the country.
Airbus stretched the A350-1000 by about 7m, making it one of the most elegant new planes.
According to Airfleets.net, Cathay Pacific's 155-strong widebody fleet is eight-and-a-half years old, which the airline says is one of the youngest in the sky.
Airbus brought an example of the A350-1000 to Auckland last year as part of a global sales push. The plane is a long-shot option to replace Air New Zealand's Boeing 777-200s from early next decade.
The advanced A350-1000, like its 900 sibling, has advanced aerodynamics, design and other technologies, providing improved fuel efficiency. Airbus says the plane offers improved fuel efficiency of up to 25 per cent on the aircraft types it replaces.
All Cathay Pacific A350 aircraft are equipped with Wi-Fi, allowing customers to remain connected throughout their journey. The planes also have jet-lag-busting technology for optimal cabin pressure.
Cathay Pacific regional general manager – South West Pacific, Rakesh Raicar, said the airline was the first to bring the Airbus A350-900s to New Zealand skies in 2016.
"We are also delighted with the increase in flights allowing more New Zealanders to experience our direct service to and from Hong Kong, and beyond to other destinations through the Hong Kong aviation hub during the busiest period of the year."
Cathay Pacific will also be extending its seasonal service period to Christchurch (previously December-February) by operating an additional three flights per week in the final two weeks of November. The service will then move to four flights per week from December until February 2020, adding an extra flight per week versus last year during the peak travel period.
These additional flights will be operated by the A350-900.
Last year, Cathay Pacific was named Airline of the Year in Auckland Airport's operation awards.
The airline has been expanding aggressively into new markets where it believes it can make topline gains after being hit by strong competition in its home market and was caught out by rising fuel prices.
During the past year it has added around 10 new destinations to its network, including summer seasonal flights to Christchurch.
The company took delivery of the first of 20 of the 1000 series planes in June last year to build its long-haul services.
The airline had some initial problems with Zodiac seats in its A350-900s introduced in 2016 but the ones in the new planes have the improvements and more robust parts.
Cathay also says the Panasonic Avionics-supplied inflight entertainment and Wi-Fi system has been enhanced and components improved.
The airline has a code-share agreement with Air New Zealand on its Hong Kong route.
Cathay's increased capacity will be welcomed by Auckland Airport, which is also preparing for a new carrier, Air Canada, this summer.