Cardiologist Elad Maor is believed to have infected a colleague at home who also received a triple injection, and both tested positive for the variant.
Doctors’ symptoms so far have been mild, according to Sheba Medical Center near Tel Aviv.
Up to 30 cases of omicron have now been detected in the UK.
Scientists do not yet know if it is more transmissible or if it causes more serious disease, but some fear that it is the most serious variant to date.
Dr Maor was at a three-day conference at the Excel Convention Center in London last month, along with more than 1,200 other people, returning to Israel on November 23.
He began to experience symptoms within days and tested positive on November 27.
He and his colleague had both received the Pfizer-BioNtech vaccine, the hospital said.
Dr Maor, 45, said The Guardian he was sure he was one of the first people in the world to be infected with the new variant, saying, “I had omicron in London for sure. It’s interesting because it was 10 days ago in London – really, really early.
He said although his wife accompanied him to London, neither she nor her children had shown any symptoms or tested positive for Covid.
Two other people in Israel have been identified as carriers of the new variant, including a tourist from Malawi who had received the AstraZeneca vaccine.
Israel closed its borders to foreigners from all countries on Saturday for two weeks in an attempt to contain the spread of Omicron, and reintroduced anti-terrorism phone tracking technology to trace the contacts of a handful of people who may have been infected. .