Westminster is to fund hotel quarantine stays for delegates travelling to COP26 from red list countries.
The move is designed to ensure that the voices of “those most affected” by climate change are heard at the landmark summit, due to be held in Glasgow in November.
Vaccines are also being offered to “accredited delegates” who would otherwise be unable to get a jab.
Alok Sharma, COP26 president-designate, stressed the event “must go ahead” this year, after the original 2020 date was postponed due to Covid-19.
The UK Government said vaccination is “very strongly recommended for everyone” planning to attend the summit.
Delegates who have registered for a vaccine through the accreditation process are set to begin receiving their first dose this week.
The offer of funding for hotel quarantine covers party delegates, observers and media arriving from red list areas who would otherwise find it difficult to attend COP26.
It is available to individuals who are both vaccinated and unvaccinated.
As it stands, delegates from red listed countries who are fully vaccinated will have to quarantine on arrival for five days, while those who are unvaccinated will have to isolate for ten days.
Decisions on travel restrictions and vaccines for COP26 have been developed by the UK Government and Scottish Government and are based on public health advice, Westminster said.
Mr Sharma said: “COP26 has already been postponed by one year, and we are all too aware climate change has not taken time off. The recent IPCC report underlines why COP26 must go ahead this November to allow world leaders to come together and set out decisive commitments to tackle climate change.
“We are working tirelessly with all our partners, including the Scottish Government and the UN, to ensure an inclusive, accessible and safe summit in Glasgow with a comprehensive set of COVID mitigation measures. This includes an offer from the UK Government to fund the required quarantine hotel stays for registered delegates arriving from red list areas and to vaccinate accredited delegates who would be unable otherwise to get vaccinated.
“Ensuring that the voices of those most affected by climate change are heard is a priority for the COP26 Presidency, and if we are to deliver for our planet, we need all countries and civil society to bring their ideas and ambition to Glasgow.”
COP26 was originally due to take place in Glasgow in November 2020 but organisers took the decision to delay it by a year in light of the pandemic.
Thousands of delegates, including world leaders, will come together to draw up plans to accelerate global decarbonisation.
The United Nations event has been described as the “world’s best last chance to get runaway climate change under control”.