Boris Johnson hails the public’s response and says the volunteers will be “absolutely crucial” in the fight against COVID-19.
Sky News understands that more than half a million people have signed up to the NHS volunteer scheme – double the original target which was set on Tuesday.
Some 504,303 have agreed to take part in the initiative,
It comes as the UK spends a second day in lockdown over the coronavirus – and as the number of deaths was confirmed to have risen to 465.
The PM said the country was coping “very well indeed” amidst the “most challenging possible circumstances”.
Mr Johnson said that “never in our history has the government put its arms around people in the way we are doing now to help them get through this time”.
He also said ministers would be examining legal ways of rallying against those profiteering by hiking up prices during the lockdown.
The government has said that a package of measures to support self-employed workers will be set out by the chancellor on Thursday.
Mr Johnson told MPs in the Commons earlier that the government would do “whatever we can” to support them.
The issue was one of a number raised during the final PMQs before the Commons breaks early for its Easter recess.
Mr Johnson also came under pressure over the official advice to the construction industry.
Construction workers can still go in as long as they can remain two metres (6.5ft) apart at all times, the government has said.
Amid reports of crowded Tube carriages in London, there have been calls for all non-emergency construction work to come to a halt in order to allow workers in that industry to stay home and avoid spreading the virus further.
London mayor Sadiq Khan has said “too many of the people using TfL services at the busiest times work in construction”, as he reiterated his call for a ban on non-safety construction work.
Mr Johnson told MPs that it should be possible to “run a better Tube system” and implement a fuller service, as the row between the government and London mayor continued.
However, Mr Khan has insisted this is not possible due to staff being off sick or self-isolating because of the coronavirus.
Parliament is breaking up early because of fears over the spread of COVID-19.
Its last task before going into recess was considering and scrutinising the government’s emergency legislation to tackle the outbreak.
The bill contains sweeping powers and has become law after it cleared the House of Lords without amendment.
Meanwhile, MPs have heard that millions of new coronavirus testing kits could be ready to order on Amazon in days, rather than weeks or months.
But Professor Christopher Whitty, chief medical officer for England, told Wednesday’s news conference he did not think people would be able to order tests on the internet next week.
He stressed that the priority would be testing frontline NHS workers, to allow them to return to work if they have already had the virus.
And he added that there was no guarantee that the lockdown would ensure that the NHS would not be overwhelmed.
“We do think that if everybody sticks to staying in your household unless absolutely essential, this gap will probably be manageable by the NHS,” he said.
“But we cannot guarantee that and nobody that is sensible would wish to guarantee that.
“But that is what we are planning for and that is what we intend to happen.”
Mr Johnson said the government was “massively ramping up our testing programmes” and wanted to be carrying out 250,000 tests a day “very soon”.
Editor: Judy Smith From Sky News