The vaccine, developed by U.S. drugmaker Merck & Co, is already being used under emergency guidelines to try to protect people against the spread of a deadly Ebola outbreak in Democratic Republic of Congo.
It protects against the Zaire strain of the Ebola virus - the one that most commonly causes outbreaks.
The shot is also being reviewed under a fast-track system by regulators in the United States, with a decision expected in the first quarter of next year.
“This vaccine has already saved many lives in the current Ebola outbreak, and the decision by European regulators will help it to eventually save many more,” the WHO’s director-general Tedros Adhanom Ghebreyesus said in a statement.
The Congo Ebola outbreak has killed more than 2,100 people since the middle of last year. It is the second-largest Ebola outbreak in history, after a 2013-16 epidemic in West Africa that killed more than 11,300.
The Merck vaccine, which the company has now brand-named Ervebo, is likely to get a full marketing license from the European Commission in a few weeks.
Roger Perlmutter, president of Merck Research Laboratories, said the company’s priority now was to get regulatory approval of its Ervebo manufacturing site in Germany so that licensed supply of the vaccine “can be used to support global public health preparedness”.
Merck’s vaccine is being used in Congo in a so-called “ring vaccination” approach, in which people who may have been in contact with someone newly infected with Ebola are traced and offered the shot to protect them.
Charlie Weller, head of vaccines at the Wellcome Trust global heath charity said the Merck shot had already saved “countless lives” in the country.
“Having this vaccine available under research conditions has been key in preventing the ongoing outbreak in the DRC spiraling into a repeat of the 2014-16 epidemic, where 11,000 people died,” she told Reuters.
Health authorities in Kinshasa said last week they planned to introduce an experimental second Ebola vaccine, developed by drugmaker Johnson & Johnson, in the country’s eastern provinces in November.
The Ebola virus causes hemorrhagic fever and spreads from person to person through direct contact with body fluids. It kills around half of those it infects.
There are currently no licensed treatments for the deadly infection, but scientists said in August they were a step closer to being able to cure it after two experimental drugs showed survival rates of as much as 90% in a clinical trial in Congo.