The public information campaign will involve adverts on TV, radio, online and billboards from today.
The UK’s chief medical officer, Professor Chris Whitty, and actor Mark Strong feature in a short clip that advises people to stay at home unless absolutely essential.
It follows on from earlier messages underlining the importance of helping to “delay” the impact of the virus.
The government has faced criticism for mixed messages on social distancing and a lack of clear public guidance.
People have appeared confused by ministers suggesting people should continue to exercise outdoors, but this prompted parks and tourist hotspots to be packed at the weekend and undermining social distancing.
London mayor Sadiq Khan has criticised the government for a lack of clarity on who is considered an “essential worker”, which is leading to people going to work unnecessarily.
In the TV advert, Whittey says: ”To help save lives, stay at home. Anyone can spread coronavirus.
“You should now only go out when absolutely necessary for food, medicine, work or exercise. Always try to stay two metres apart. Do not meet others outside your household, even friends and family.”
It ends with Strong saying: “Stay home. Protect the NHS. Save lives.”
The new advert comes as Downing Street has reportedly recruited Isaac Levido, who headed up the Conservative Party’s general election campaign at the end of last year, to help with Covid-19 communications.
He is said to have crafted the successful “Get Brexit Done” slogan and will join veterans of the Vote Leave campaign at the heart of Boris Johnson’s PR team.
On Monday night, the prime minister put Britain on lockdown as he outlined strict new measures to curb the spread of Covid-19, ordering people to only leave the house for a few specific reasons.
The UK’s coronavirus death toll now stands at 422 – an increase of 87 since Monday.