Prime Minister Boris Johnson has ordered all UK gyms, health clubs, leisure centres and restaurants to close at the end of business on 20 March.
Speaking at his daily press conference, Johnson also said that cinemas, nightclubs, cafes, pubs and bars will be asked to close "as soon as they reasonably can – and not reopen tomorrow".
Johnson said the "extreme measures" will help save lives.
"These actions will help take the strain off the NHS and we will be able to save literally thousands of lives," he said.
The decision to close leisure outlets was made after evidence suggesting that the government's recommendation for social distancing was being ignored, especially in cities and towns.
Earlier in the day, Tim Martin, boss of pub chain JD Whetherspoon, drew widespread criticism after suggesting that shutting pubs over the coronavirus outbreak would be "over the top" – and that they should stay open "for the duration" of the pandemic.
Other measures introduced during the PM's press conference will see businesses offered "unprecedented" financial support.
Chancellor Rishi Sunak, speaking alongside the PM, announced that business could apply for grants to ensure they do not have to let staff go due to the slowdown in the economy.
He said that the government would pay 80 per cent of wages for employees not working, up to £2,500 a month, as part of efforts to avoid widespread job losses.
He also announced that he would defer the next quarter of VAT payments for firms, until the end of June.
Commenting on the government's decision, leisure industry bodies said the sector would follow all government guidance and "always put the health and wellbeing of its customers and staff at the heart of its work".
"Following the Prime Minister’s announcement today (20 March) telling the fitness and leisure sector to close its facilities, we will be working with our members to support them over the coming hours, given the timeline provided," a joint statement from ukactive, Community Leisure UK and the Chartered Institute for the Management of Sport and Physical Activity (CIMSPA) reads.
"We have been lobbying hard for urgent support for the sector and we welcome the announcements around payroll support within the Coronavirus Job Retention Scheme, the extension of interest-free loans for 12 months, the delay in VAT payments, and access of funding to include large and small organisations.
"Over the coming hours and days, it is crucial we work with the government and its agencies to access fully the financial support pledged by the Chancellor in his statement. The ability to access this funding will determine how we cope and come out of this situation once the crisis has abated.
“However, we remain unclear around the issues of rental payments and overheads for facilities – and support for the self-employed – and we will work to seek greater clarity on these issues with the government.
"Our members will continue to support their customers even though the physical facilities will be closed – adapting and finding innovative new ways to help people to maintain active lives. We will continue to keep our nation healthy and active in the most challenging of times.
"The fitness and leisure sector will reopen its facilities when it is safe to do so – and will do so with increased vigour and the energy that has always been its hallmark."
The order to close doors – and the support offered to businesses – was also welcomed by the pub industry.
Emma McClarkin, CEO of the British Beer and Pub Association, said: "The safety and wellbeing of people is our priority. We stand ready to play our part in the fight against COVID-19 and in the process protecting our communities and employees.
"As a sector employing nearly one million people, the Chancellor’s support package announced today on staff wages will safeguard thousands of livelihoods and help closed pubs try to get through this difficult period.
"We stand ready to work with the government to ensure that the support is accessible as fast as possible.
"There remain areas where we need further support to sustain our great brewing and pub sector through this difficult time, to ensure that all staff will have jobs to return to and to guarantee all pubs can reopen again when this crisis is over and continue to be at the heart of communities up and down the country."