Travellers in quarantine hotels in England were told they could leave on Wednesday afternoon (December 15), as long as they have tested negative for Covid.
Health secretary Sajid Javid also confirmed guests will be refunded for the days they have not used.
Their release came after the government took all 11 countries off its travel red list earlier on Wednesday.
The change was announced on Tuesday because the Omicron variant of Covid has spread so widely across the UK.
The BBC reported that a letter from the Department for Health had allocated hotel guests time slots to leave, organised by floor, from 4pm onwards on Wednesday.
People were advised they were required to stay until formally told they can leave.
Anyone who tested positive must continue to complete their quarantine at the hotels, as must unvaccinated guests who have been in contact with someone who has tested positive.
There were reports that some travellers had already left their quarantine hotels on Wednesday morning before their formal release.
About 5,000 people had to use the hotel quarantine system since countries were put back on the red list in late November.
The Telegraph reported that guests were told they had to continue their isolation at home.