The ban goes into effect on Monday – when Bulgaria, Croatia, Hong Kong and Taiwan will be moved to the UK’s green list for travel without quarantine.
The Balkan nation is a popular destination for package holidays and for those looking for an affordable beach break in the south of the country.
Hopes rose when UK transport secretary Grant Shapps said people returning from Bulgaria would no longer need to isolate themselves from 19 July.
But holidays there are out of the question once again after Bulgaria has added the UK to its own “red zone” travel list, along with Cyprus, Spain, Fiji and Kuwait.
Previously, it had placed the UK in its amber zone, meaning visitors were allowed if they were fully vaccinated, recovered from the virus or had a recent negative PCR test.
But its new policy, announced by Health Minister Stoycho Katsarov, means people planning to visit the UK will likely have to cancel their trip.
People from Red Zone countries will only be allowed in Bulgaria for limited reasons.
This includes whether they are Bulgarian citizens, and some exemptions are being made, such as for medical professionals and seasonal workers.
The news comes after the daily number of new coronavirus cases in the UK has risen to over 50,000 for the first time in six months
It was the second blow to the British holiday industry in just a few hours.
Earlier, it was announced that an unquarantined trip to France would not be possible for dual-punishment residents.
From Monday, anyone who is double vaccinated more than 14 days after the trip will be allowed to visit the countries on the amber list without having to isolate themselves on their return.
But the new system will not apply to France, which has seen an increase in cases of the Beta variant that first emerged in South Africa.