The UN Human Rights Council announced it will convene a special session on Thursday to address alleged Russian human rights violations during its war in Ukraine.
More than 50 countries on Monday backed a request from Kyiv and demanded an extraordinary meeting of the UN's top rights body to examine "the deteriorating human rights situation in Ukraine stemming from the Russian aggression".
Yevheniia Filipenko, Ukraine's ambassador to the UN in Geneva, said it would send a strong signal to Russian President Vladimir Putin about Moscow's international isolation.
"Together, we are sending another strong message to Putin and his clique of war criminals: you are isolated as never before," she said in a video message on Twitter.
"We want to see the UN take practical steps to address Russia's violation of human rights in Ukraine and the war crimes which it commits daily against our people.
"This includes an investigation by the Commission of Inquiry into Russia's crimes committed in Bucha and other liberated areas.
"This is also an opportunity for the international community to focus on the situation in Mariupol, as well as forced transfers of our population, and other violations and abuses against innocent Ukrainian civilians.
"We will not rest until we ensure that those who commit these crimes are held to account."
The meeting will convene at 0800 GMT and be webcast live in the six official UN languages.
The support of 16 members of the council -- a third of the membership -- is required to convene a special session.
The call received the backing of members including Britain, France, Germany, Japan, Mexico, the Netherlands, Poland, South Korea, Ukraine and the United States.
Outside the council, observer states including Canada, Colombia, Italy, Moldova, New Zealand, Norway, Peru, Portugal, Spain, Sweden, Switzerland and Turkey backed the call.
British ambassador Simon Manley tweeted that he was proud that the UK was standing with Ukraine in calling for a special session "in the face of the appalling atrocities being perpetrated in Mariupol and elsewhere in Ukraine".
"Accountability matters," he added.
Russia was a member of the Human Rights Council until the UN General Assembly in New York voted on April 7 to suspend them from the body and from sitting in judgement of other nations' human rights records.
Russia then immediately withdrew from the council.
It will only be the 34th extraordinary meeting of the UN's top rights body since its creation in 2006.