MPs will vote later on the government’s month-long lockdown in England, amid growing unease among Conservatives about the economic and social impact.
The restrictions will come into force just after midnight if approved, and will last until 2 December.
Pubs, restaurants, gyms and non-essential shops will have to close.
England’s chief medical officer said “economically and socially destructive” lockdowns are the only practical option to stem the spread of Covid-19.
Prof Chris Whitty said that would remain the case until a vaccine and better drugs become available.
A number of Conservative MPs have criticised the nationwide lockdown.
However, Labour’s support for the new measures mean they are highly likely to be approved even if there is a rebellion from Tory backbenchers.
Labour first called for a short lockdown or “circuit-breaker” in England last month and have criticised the government for not acting quickly or decisively enough.
BBC political correspondent Iain Watson said that Labour’s support will be enough to deter some Tories who have criticised the measures from rebelling, because they would see it as a “senseless sacrifice”.