Speaking in Auckland on Monday Air New Zealand chief executive Christopher Luxon said it had eight firm orders for the new aircraft and an agreement with Boeing includes an option to increase the number of aircraft from eight to up to 20.
The deal is worth US$2.7 billion (NZ$4.12b). Air New Zealand has negotiated a significant discount on current list prices and the parties have agreed not to disclose the actual purchase price.
Luxon said it had "big ambitions" to fly Auckland to New York with its newly ordered aircraft but also using its existing Boeing 787-9 Dreamliners under a reconfigured cabin.
The 787-10s would be powered by General Electric's GEnx-1B engines. he said.
The national carrier said in September it was in the market for a new type of wide-body aircraft to replace its Boeing 777-200ERs - the oldest wide-body aircraft in Air New Zealand's fleet.
Air New Zealand already has 13 Boeing 787-9 Dreamliners in its fleet with one more on order.
They have an average age of nearly three years.
Air New Zealand has nine 777-200ERs with an average age of nearly 14 years.
In June 2004, Air New Zealand bought eight new Boeing 777-200ER. The aircraft began arriving in October 2005 and allowed Air New Zealand to develop new routes and increase frequency on existing routes.
In July 2014 Air New Zealand became the first airline to take delivery of a 787-9 - the stretch version of Boeing's Dreamliners.
Its first Dreamliner touched down in Auckland a few days later and began its first scheduled flights in October 2014.
The first of the highly fuel-efficient aircraft will join the Air New Zealand fleet in 2022 and together they will have the potential to save 190,000 tonnes of carbon per year.
"This is a hugely important decision for our airline. With the 787-10 offering almost 15 percent more space for customers and cargo than the 787-9, this investment creates the platform for our future strategic direction and opens up new opportunities to grow," Luxon said.
Representatives from the aircraft and engine manufacturers were in attendance.