The money, which will be split between 117 trusts, comes amid attempts to reassure the public that it is safe to visit emergency departments during the pandemic.
“Thanks to the hard work and tireless efforts of NHS staff throughout the pandemic, our A&Es have remained open for the public,” the Prime Minister said in a statement.
“It is vital that those who need emergency treatment this winter access it, and for those who remain concerned about visiting hospitals, let me assure you that the NHS has measures in place to keep people safe,” he said.
Hospitals will be able to use the funding to expand waiting areas to ease overcrowding and increase the number of treatment cubicles to boost capacity.
It could also enable hospitals to increase the provision of same-day emergency care and improve patient flows to help them to better respond to winter pressures and the risks of fresh coronavirus outbreaks.
Officials said the projects would all be completed by the start of 2021 so hospitals would benefit from the upgrades during the peak months of winter.
Mr Johnson said: “These upgrades will help our fantastic NHS prepare for the winter months, helping them to deliver essential services and reduce the risk of coronavirus infections.”
It comes on top of a £3 billion cash injection for the NHS in England – with extra funding also for Scotland, Wales and Northern Ireland – announced last month to help it to cope with the expected winter pressures.
That funding has been earmarked to enable the NHS to continue to use the extra hospital capacity acquired from the independent sector, maintain Nightingale hospitals until the end of March and expand its flu vaccination programme.
Dr Nick Scriven, immediate past president of the Society for Acute Medicine, said while any additional funding was helpful, there were limits to what it could achieve.
“The money is welcome but how do we think we can actually implement what would be building works in existing units whilst remaining safe and efficient – all before any rise in either Covid or non-Covid patients which, if like last winter, may start before the end of October?” he said.