In a letter to the prime minister, the 6,200 signatories warned healthcare workers have been left feeling like "cannon fodder" in the battle against COVID-19.
Arranged by Dr Rinesh Parmar, the chair of the Doctors' Association, the letter stated: "We are pleading with you to intervene to ensure NHS staff have adequate personal protective equipment (PPE) when facing the COVID-19 pandemic.
"Frontline doctors have been telling us for weeks that they don't feel safe at work, with many reporting they do not have access to PPE recommended by Public Health England."
The letter added it is "simply unacceptable" that those working in intensive care have reported having to put ventilators on coronavirus sufferers with masks that expired in 2015, while workers in other areas have either seen their stocks run out or only have days left.
"The reality is that many of us will get sick," it continued.
"Doctors are all too aware of the possibility that they will lose colleagues, as has happened in outbreaks around the world.
"It is therefore deeply upsetting to hear dedicated healthcare professionals say that they feel like 'cannon fodder'."
The signatories urged Mr Johnson to "demonstrate your commitment to the NHS and protect the lives of the life-savers".
It comes as two NHS ear, nose and throat consultants are receiving critical care after contracting coronavirus from infected patients.
The ENT medics are on ventilators and "most likely" acquired the highly contagious respiratory infection from people who did not show any symptoms.
Professor Nirmal Kumar, the president of ENT UK, told Sky News: "We sadly have two consultants who are on ventilators in this country and most likely having acquired the infection from passive carriers in the course of their daily clinical work.
"We are in strong support of the prime minister's request for social distancing and also recommend that full PPE is made available for those clinicians dealing with such work and in close contact with patients."
Labour leader Jeremy Corbyn also said the UK had to "be better" at providing protective equipment to healthcare workers.
He told Sky News' Sophy Ridge on Sunday: "NHS staff have not all got full protective equipment at the moment or protective clothing.
"Care staff have almost none at all and care workers, some of whom work in care homes, are obviously at risk but even more at risk are the care workers who are going from house to house of their clients and clearly are in danger of either contracting or spreading the virus."
Housing Secretary Robert Jenrick said the government was "working very hard" to ensure more PPE is available, but admitted "there is more to do".
"Everybody who is on the frontline, supporting us as a country through this crisis, must have the equipment that they need to do their job and to be personally protected," the cabinet minister told Sophy Ridge.
"We are working very hard, with success, to get more PPE available, I think by this afternoon we will have delivered
more supplies to hospitals across the country.
"We have delivered supplies to GP surgeries and to pharmacies and next week all social care providers will receive further supplies.
"We are manufacturing and importing large quantities and I think in recent days we have received three million masks for example but I completely accept there is more to do.
"We are manufacturing and importing more and we need to get that to the frontline as quickly as possible."
Mr Jenrick also revealed the country now has 12,000 ventilators, which follows a call to British industry to help produce the vital machines.
Last week, Health Secretary Matt Hancock said the UK had 5,000 ventilators but needed many more times that number.
Ex-health secretary and former Conservative leadership contender Jeremy Hunt, who is now chair of the House of Commons health committee, said the NHS had "moved heaven and earth" to get protective equipment into hospitals.
He told Sophy Ridge: "A lot has changed in the last week and we have had lorries on the road pretty much every day going around the country.
"We had a very difficult committee hearing on Tuesday in which we raised these issues to Sir Simon Stevens [chief executive of NHS England] and the NHS really has moved heaven and earth to get protective equipment out to every hospital."