Travellers arriving in England will be able to cut their quarantine time by more than half if they pay to take a private Covid-19 test after five days.
Under the test and release plan, people will be allowed to leave quarantine early after returning a negative result to a test provided by a private firm.
The rules come into force from December 15 and the tests can cost up to £120 ($160).
The test would be administered on the fifth day with results returned within 24 to 48 hours.
This means people could leave six days after arrival.
If they test positive, however, travellers have to remain in isolation for the full 14 days.
The new quarantine system comes a day after UK Prime Minister Boris Johnson announced England's lockdown would end on December 2 as planned.
It also follows news that a vaccine developed by the University of Oxford and AstraZeneca is up to 90 per cent effective.
UK Transport Secretary Grant Shapps said the “complicated” test and release system took months to set up despite calls for urgency from the struggling airline industry.
He told Sky News: “You've got to match up the medical ability with the science, as it were, with the number of days capacity which is or isn't available – which has been difficult despite having the biggest amount of testing in Europe.”
He earlier told The Telegraph the arrangements were a "stepping stone" to quarantine-free travel.
"I also think it is a stepping stone to the next stage which is lateral flow testing so you don't have to quarantine at all," he said.
"You just test every day for a week. We know that is coming but we're not going to get that going until the new year and then finally there will be the vaccine to take us out of this."
But Ryanair chief executive Michael O’Leary said “test before you travel would be a much better system”.
He told BBC Radio 4's Today programme: "There is always that theoretical risk (of becoming infected during the journey) but that is still a much better system than allowing someone into the country with no testing whatsoever."
Tests are expected to cost between £65 and £120 per passenger.
People arriving by air, ferry or rail have to book a private screening and quarantine prior to arrival, and a list of permitted testing providers will be published by the Department for Transport next month.
Those who choose not to be tested must observe a two-week quarantine.
The government said the private sector would take the tests to avoid putting pressure on the NHS.
The new strategy is accompanied by a financial support plan for commercial airports in England.
Mr Shapps promised support capped at £8 million per airport, with funding to be released next year alongside a plan to restart the cruise industry.
Chancellor Rishi Sunak said: "The aviation industry is vital to our economy – creating jobs and driving growth.
"This new package of support for airports, alongside a new testing regime for international arrivals, will help the sector take off once again as we build back better from the pandemic."
Others in the airline industry welcomed the plan but said it was long overdue.
Virgin Atlantic chief executive Shai Weiss said the new rules were “a vital first step to reopening the skies in the run-up to Christmas”.
“A five-day quarantine is likely to prove a significant deterrent for travellers, especially those on business,” he said.
British Airways chief executive Sean Doyle added: “We know there is pent-up demand for travel and we support any move which will help get Britain and the economy flying again.”