All McDonald's sites will close by 7pm tonight, after the group said maintaining social distancing while offering drive-thru and takeaway services had become "increasingly difficult".
The announcement followed prime minister Boris Johnson's Sunday evening press conference in which he reiterated calls for people to stay at home, with coronavirus at risk of overwhelming the NHS.
McDonald's UK boss, Paul Pomroy, said: "Over the last 24 hours, it has become clear that maintaining safe social distancing whilst operating busy takeaway and Drive Thru restaurants is increasingly difficult and therefore we have taken the decision to close every restaurant in the UK and Ireland by 7pm on Monday 23 March.
"I have been clear throughout this that we would only continue to operate whilst it was safe for our people and together with our franchisees, we feel now is the time to make this decision."
Ahead of the shutdown, NHS workers will be given free food and drink on sight of identification.
Around 340 Nando's stores have also closed for the foreseeable future after moving to a delivery operation following Friday's announcement from Johnson that all restaurants, pubs and cafés should close, with 80% of wages to be covered by the government.
In a statement, the restaurant group said: "The health and safety of our customers and team is our highest priority."