From big Wall Street banks to corner grocery stores, all private employers in New York City will have to require their workers to get vaccinated against COVID-19 from December 27.
The order goes further than a nationwide mandate set by President Joe Biden for companies with more than 100 employees to vaccinate workers by January 4 that has been stalled by court suspensions.
"As of today we are going to announce a first-in-the-nation measure – our health commissioner will announce a vaccine mandate for private sector employers across the board," said New York mayor Bill de Blasio.
"This is how we put health and safety first, by ensuring that there is a vaccine mandate that reaches everyone universally in the private sector."
Vaccinations are already required for city employees including teachers, police officers, and firefighters, and a vaccination mandate for employees of private and religious schools was announced last week.
Vaccine mandates have a long history in the US but have generally been issued by cities or states.
De Blasio cited the emergence of the coronavirus Omicron variant, cold winter weather, and holiday gatherings as "additional challenges" to tackling the pandemic in New York, which was hit hard by the virus in 2020, with at least 34,000 deaths.
New York City is averaging just under 2,000 new cases of COVID-19 per day, up from about 820 a day at the start of November.
Omicron cases have been confirmed in at least 15 US states since it was first reported in late November, including several in New York, with de Blasio saying he was "very concerned".
"We in New York City have decided to use a pre-emptive strike to really do something bold to stop the further growth of COVID and the dangers it's causing to all of us," he said.
Apart from the mandate, which would cover some 184,000 businesses and companies, he said there will be other measures to "focus on maximising vaccination quickly so we can get ahead of Omicron and all the other challenges we are facing right now with COVID-19".
The Greater New York Chamber of Commerce, which includes some 30,000 businesses big and small, said it supports the tightened measures.
"This is for the health and public safety to keep the economy growing, to keep tourists feeling safe when they come here," Mark Jaffe, President of the Greater New York Chamber of Commerce said.
"We don't want to be a headline 'New York City is leading the nation in COVID', we don't want to lead the nation in COVID rates, and this is an important step."
But other industry groups said the plan would add to the strain on businesses still struggling to recover from the pandemic and find enough employees.
However, De Blasio said he expects the new mandate to survive any legal challenges and added that he will release more details next week about how the mandate will be enforced.
US health experts have strongly urged people to get their shots and a booster, saying they believe the vaccine will still offer protection against the new variant.