Transport Secretary Grant Shapps has said everyone travelling on public transport in England will be required to wear a face covering from June 15.
The Government has announced the change,which it says will help contain the spread of the virus as people begin to return to work in greater numbers later this month.
Travellers could be fined or refused permission to board buses or trains if they refuse to comply with the order.
In May, the government advised the public to wear DIY face masks for some shopping and using public transport.
London Mayor Sadiq Khan previously called for face masks to be made compulsory.
At the Downing Street press conference Mr Shapps said: "I can announce that as of Monday June 15 face coverings will become mandatory on public transport.
"That doesn't mean surgical masks, which we must keep for clinical settings. It means the kind of face covering, you can easily make at home. There will be exemptions to these rules for very young children, for disabled people and those with breathing difficulties."
He said "we need to ensure every precaution is taken on buses, trains, aircraft, and on ferries".
"With more people using transport the evidence suggests wearing face coverings offers some - albeit limited - protection against the spread for the virus."
In response to the announcement London Mayor Sadiq Khan said: “I’m pleased that our lobbying has paid off and the Government has finally seen sense and made it mandatory for people to wear face coverings on public transport. This is something I and others have been calling on ministers to do for some time, and is in line with a large body of evidence that they can help stop the spread of coronavirus.
“I encourage anyone travelling on public transport, or anywhere you can’t keep a safe 2 metre distance, to wear a face covering, but from Monday 15 June, everyone must wear a covering over their nose and mouth for the entirety of any journeys made using the public transport network. This will be mandatory and will help everyone be safer.
“TfL continues to work hard to maximise services despite staff being ill, shielding or self-isolating. The reality is that due to social distancing the effective capacity of public transport services has been dramatically reduced. We can only carry between 13% - 15% of passengers. We all must play our part by working from home if we can and making journeys on foot or by bike if at all possible in order to keep the service safe for those who really need it. I want to thank Londoners who have made monumental sacrifices over the last ten weeks and stuck to the rules. I urge them to continue to do so to help save lives.”
Confederation of Passenger Transport Chief Executive Graham Vidler said: "Buses are already safe to use as operators have introduced enhanced cleaning regimes alongside other measures including restricting capacity, but making face coverings mandatory will give more passengers the confidence to travel.
"We will need passengers to work with us and wear their own face covering to comply with this new requirement.
"We will also work with the Government on its implementation, including increasing capacity in the network and maximising the value of the bus in safely restarting our economy and daily life."
