Morrisons is selling petrol for less than £1 per litre at its garages around the country.
The supermarket said this is the first time the fuel has been “sold nationally” for less than £1 per litre since February 2016.
It has also cut its diesel price to no more than 104.7p per litre.
The chain said the maximum price drivers will pay is 99.7p per litre at its UK forecourts.
Morrisons’ head of fuel Ashley Myers said: “This cut will help people who are travelling to work, those shopping for essentials, and those assisting the elderly and vulnerable.
“We want to play our full part in reducing the cost of living and feeding the nation at this difficult time.”
Government figures show the average cost per litre and petrol and diesel on May 4 was 107.6p and 114.9p respectively.
The price collapse means filling a 55-litre family car is around £7 cheaper than seven weeks ago.
The reduction in the cost of fuel has been driven by a collapse in oil prices due to lower demand as global economies shut down because of the coronavirus pandemic.
Brent crude oil was trading at around 64 US dollars per barrel at the beginning of the year but sunk to under 19 dollars last month.
The price hovered around 31 dollars per barrel on Monday morning.
The number of UK motorists taking advantage of cheaper fuel is limited because the Government has restricted the reasons for people being allowed to leave their home, although Boris Johnson said on Sunday that people can now “drive to other destinations”.
Department for Transport figures released last week showed that road traffic was around 58 per cent lower than in early February.
RAC fuel spokesman Simon Williams said: “Although the lockdown is far from over, yesterday’s speech from the Prime Minister was a signal to drivers that they can begin to make more trips by car again – so credit is due to Morrisons for taking the lead and selling petrol and diesel at what is a very fair price and one that is much more reflective of what the retailer is itself paying to buy the fuel in.
“Unfortunately though, there is a darker side to any large price cuts – they heap yet more pressure on smaller independent fuel retailers, who in some cases are already fighting for survival as a result of the coronavirus outbreak.
“It remains to be seen how long prices this low will persist for, with some early indications that wholesale petrol prices have started to rise as a result of the world oil price creeping up.”