Tickets for new direct flights linking Australia and Europe are now on sale.
Qantas' Perth-London flights begin on March 24 next year aboard the airline's new Boeing 787-Dreamliner.
The 17-hour flight is 14,498km, just a little under what is currently the world's longest flight, Qatar Airways' Auckland-Doha service.
The new Qantas flight will replace its existing Melbourne-Dubai-London services - marking the next evolution of the "Kangaroo Route", seven decades after the national carrier first flew Australians all the way to London.
Qantas Group chief executive Alan Joyce said there had been global interest in the Perth-London flights since they were announced in December 2016.
"The Kangaroo Route has kept changing with new technology. It used to take four days and seven stops but now we're able to link Australia and UK in a single hop. It's a level of convenience Australians have never had before.''
Joyce said the airline was conscious that this was a long flight but the kind of route that the Dreamliner was created for, because of its built-in features to reduce jet lag and improve the overall travel experience.
"We've added a very high level of comfort in each of the cabins and a lower seat count than most of our competitors," he said.
"And we're making tweaks to our in-flight service designed to help customers enjoy the journey more."
Year round return economy fares for the Melbourne-London and Perth-London routes start from A$2270 (NZ$2459) but are expected to drop below A$2000 during sale periods.
Year-round return premium economy fares start from A$4450 between Melbourne and London and from A$4250 between Perth and London.
Year round return business-class fares start from A$9890 return between Melbourne and London and from A$9725 between Perth and London.
Merrill Lynch analysts estimate the 787-9 is 34 per cent more fuel efficient than the A380 it will replace.
The Qantas A380 that currently operates the Melbourne-London route will be redeployed to meet periods of high demand from Melbourne and Sydney to destinations in Asia, such as Singapore and Hong Kong.
Currently, Qantas flies seasonally between Auckland and Perth (between November and April) and passengers will be able to connect directly during this time. During other times customers from New Zealand travelling to London and Europe will travel via Sydney on QF's A380 service.