In a statement, chief executive Paul Pomroy wrote: "Our restaurants will remain open for as long as it is safe to do so.
"In the last 24 hours it has become clear that we need to temporarily change our operations to ensure the wellbeing of our employees and customers consistent with the Government's guidance on social distancing.
"Therefore from 5am tomorrow (Wednesday) morning all restaurants will close seating areas and temporarily move to being takeaway, drive-thru and McDelivery only."
All restaurants will scrap dine-in operations, shut seating and close children's play areas, but toilets will remain open.
He added that all orders placed through Uber Eats and Just Eat would be "contact-free, with no physical contact between customers, employees and couriers, wherever possible".
Workers in the emergency services and health and social care sectors will receive free drinks on presentation of their work pass.
The chain's annual Monopoly promotion is being paused until later in the year, the company added.
Mr Pomroy said: "This year's prizes include a number of luxury holidays, European city breaks and cruises which will have all been impacted by current and ongoing restrictions on international travel.
"Following conversations with our suppliers and prize partners, we feel it is appropriate to delay the promotion until later this year."