United Airlines aims to be the first carrier to resume supersonic travel since the demise of Concorde 18 years ago.
Flights by US-built Boom Supersonic Overture aircraft could be operating between New York (Newark) and London Heathrow in just three and a half hours, knocking three hours off the existing journey time.
United is to buy 15 aircraft initially for possible introduction into passenger service by 2029.
The US carrier has an option on a further 35 Overtures, which will be capable of flying at Mach 1.7 – twice the speed of current commercial aircraft.
United believes Overture can connect more than 500 destinations in nearly half the time, carrying between 65 to 88 passengers depending on configuration.
Besides London, other future potential routes include Newark to Frankfurt in four hours and San Francisco to Tokyo in six hours.
Overture will feature in-seat entertainment screens, ample personal space, and contactless technology.
The new generation high-speed plane is expected to be the first large commercial aircraft to be net-zero carbon from day one, running on 100% sustainable aviation fuel (SAF).
Overture is due to roll out in 2025, fly in 2026 and expected to carry passengers by 2029.
United and Boom will work together to accelerate production of greater supplies of SAF.
The airline’s chief executive Scott Kirby said: “United continues on its trajectory to build a more innovative, sustainable airline and today’s advancements in technology are making it more viable for that to include supersonic planes.
“Boom’s vision for the future of commercial aviation, combined with the industry’s most robust route network in the world, will give business and leisure travellers access to a stellar flight experience.
“Our mission has always been about connecting people and now working with Boom, we’ll be able to do that on an even greater scale.”
Blake Scholl, founder and chief executive of Denver-based Boom Supersonic, added: “The world’s first purchase agreement for net-zero carbon supersonic aircraft marks a significant step toward our mission to create a more accessible world.
“United and Boom share a common purpose – to unite the world safely and sustainably.
“At speeds twice as fast, United passengers will experience all the advantages of life lived in person, from deeper, more productive business relationships to longer, more relaxing vacations to far-off destinations.”