The announcement means that limits on numbers for sports events, pubs and cinemas will remain in place, nightclubs will stay closed and people will be encouraged to keep up social distancing and working from home.
Mr Johnson said it was "sensible to wait a little longer" to try and meet the target of double vaccinating two thirds of adults, everyone over the age of 50, frontline health and care workers.
He said: "The objective is to use these valuable, crucial weeks is to save thousands of lives that otherwise would be lost by vaccinating millions of people as fast as we can."
The aim now is to offer everyone over the age of 18 their first dose by by July 19.
The latest figures show cases were growing by 64 per cent per week and in the worse affected areas doubling every week.
There had been a 61 per cent increase in the number of hospitalisations in the North West in the week to June 12, and 50 per cent in England.
Mr Johnson said although the link between hospitalisation and death had been weakened, numbers in intensive care were rising.
Professor Chris Whitty said cases of the Delta variant were going up "exponentially" and a four week delay would "reduce the risk of a very high peak that could cause significant problems in terms of pressure on the NHS".
However the 30-person cap for wedding ceremonies and receptions, as well as wakes, will be lifted from June 21, with limits to be set by venues based on social distancing requirements.
The delay has been met with anger by some Tory MPs, with a vote on Wednesday for the Government to be given the legal powers to extend the restrictions expected to lead to a possible Conservative backbench rebellion.
York Outer MP Julian Sturdy said he was certain that "the damage caused by this 4-week delay will be worse than any risk posed by the virus".
He knew from talking to businesses and constituents that many "sadly do not have the luxury of a few extra weeks. Businesses are at breaking point having already invested depleted savings to make their premises compliant with restrictions to then have any prospect of profit snatched away as trade is limited for a few extra weeks.
"A grave health crisis is mounting as waiting times for cancer, Alzheimer’s, Parkinson’s and other ailments grow by the day as the NHS still must have primary focus only on Covid-19, despite our leading vaccination programme protecting the most vulnerable and cutting hospitalisations by over 80 per cent.".
Sheffield City Region mayor Dan Jarvis said the Government had to continue its economic support for businesses. After a "horrendous" year for hospitality and for the music and entertainment industry, vast amounts of preparation would have gone into reopening on June 21, with many selling tickets, buying stock and hiring staff.
He said: "If restrictions remain, then support must remain too. That means no drop in furlough payments, no change to business rates relief and no lifting of the safeguards preventing evictions.”
Managing director of Shipley-based Saltaire Brewery Ewen Gordon said they'd already had to make a lot of adaptations to how they worked and some of the changes he believes will stay - like table service and ordering by app. The most important thing was "confidence". He said: "We don't want a review every four or five weeks. We are hoping - and all the evidence suggests it - that a few more weeks of vaccinations and we can all start having confidence to live our lives and get our normality back."