Up to 40 London Underground stations are to close in a partial shutdown.
Transport for London said it will still run a reduced service in the capital in order to allow critical workers to make essential journeys.
From Thursday, up to 40 Tube stations that do not interchange with other lines will be closed until further notice.
From Friday there will be no Waterloo & City line, while the Night Tube will not run until further notice.
London buses will operate fewer services, but still run at night, and everyone will be urged not to use public transport for anything other than essential journeys.
Mayor of London Sadiq Khan said: "People should not be travelling, by any means, unless they really, really have to. Londoners should be avoiding social interaction unless absolutely necessary, and that means they should be avoiding using the transport network unless absolutely necessary.
"London will get through these extraordinarily challenging times, and ensuring the capital's critical workers can move around the city will be crucial.
"Frontline staff across our health and care service - as well as those ensuring Londoners stay safe and can access food and other essentials - should be commended for their hard work. We owe it to them to do whatever we can to help them do their jobs effectively.
"I'm urging Londoners to only use public transport for essential journeys. Everyone should follow this and the other advice to help keep themselves and each other safe."
TfL said it would also be gradually reducing the frequency of services across the network from Monday, "to provide a service for critical workers to get to where they need to - ensuring that remaining services are not overcrowded".London Overground, TfL Rail, the DLR and London Trams will also be running fewer services from next week.
Transport Commissioner Mike Brown said: "The advice from Government is clear - people should now only be making journeys that are absolutely essential. We and our staff are doing everything we can to ensure that people who need to make essential journeys can continue to do so."
Passengers are being urged to check their journey on the Transport for London site before they travel.
Coronavirus: Everything you need to know:
Bakerloo LineLambeth North, Regents Park, Warwick Avenue, Kilburn Park, Charing Cross
Central LineHolland Park, Queensway, Lancaster Gate, Chancery Lane, Redbridge
Circle LineBayswater, Great Portland Street, Barbican
District LineBow Road, Stepney Green, Mansion House, Temple, St James's Park, Gloucester Road
Jubilee LineSwiss Cottage, St John's Wood, Bermondsey, Southwark
Northern LineTuffnell Park, Chalk Farm, Mornington Crescent, Goodge Street, Borough, Clapham South, Tooting Bec, South Wimbledon, Hampstead
Piccadilly LineCaledonian Road, Arsenal, Covent Garden, Hyde Park Corner, Bounds Green, Manor House
Victoria LinePimlico, Blackhorse Road