Australia's national carrier says it will connect Perth, in the west of the country, to the UK capital using Boeing 787-9 Dreamliners.
The 9,000 mile (14,498km) flight will take 17 hours.
Perth will be a hub for passengers from eastern Australia going to the UK, tourism minister Steven Ciobo said.
He also said the new service would boost employment and tourism in Australia, a sector growing three times faster than the rest of the national economy, and one that supports 580,000 jobs.
Mr Ciobo also said that the UK was Australia's third-largest source of international visitors, with 660,000 people travelling from there to Australia in 2015.
"When Qantas created the Kangaroo Route to London in 1947, it took four days and nine stops," Qantas chief executive officer Alan Joyce said.
"Now it will take just 17 hours from Perth non-stop."