Martin Lewis warned that lives will be lost this winter unless there is further government help with energy bills.
The money saving expert described the news that the energy price cap will soar to £3,549 in October as a “catastrophe”.
He warned that people were in an “absolutely horrendous situation” that is going to get “even worse” in January.
Millions of Brits face fuel poverty after it was announced that the average energy bill will be hiked by more than 80 per cent in the autumn.
Charities warn that many face hardship during the colder months when they are forced to choose between “eating or heating”. It has also heaped pressure on the next prime minister to act.
Lewis told BBC Radio 4′s Today programme: “The new price cap that is coming in on the first of October is 37 per cent of the new state pension, a bigger proportion of the old state pension for people who retired earlier and an even bigger proportion for somebody on Universal Credit.
“I’ve been accused of catastrophizing over this situation. Well, the reason I have catastrophized is this is a catastrophe, plain and simple - unaffordable.
“Let’s just amplify what the boss of Ofgem said earlier, he effectively said in the polite way that a regulator does ‘this is out of our hands, it is beyond our power, we need government intervention’. And we do.
“If we do not get further government intervention - on top of what was announced in May - then lives will be lost this winter by too many people to think about because of these unaffordable, terrible rise in energy bills.”
Ofgem CEO Jonathan Brearley said it was “clear” that the new prime minister will need to “act further” to tackle the impact of the price rises that are coming in October and next year.
He added: “We are working with ministers, consumer groups and industry on a set of options for the incoming prime minister that will require urgent action.”
Tory leadership hopeful Rishi Sunak has promised more money to help with energy bills, while frontrunner Liz Truss pledged to immediately reverse the rise in national insurance.
Truss, who was previously skeptical of “handouts”, has now pledged in today’s Daily Mail to deliver “immediate support” and “decisive action” if made prime minister.
The current chancellor Nadhim Zahawi said he knew the announcement would cause “stress and anxiety” for many people, but stressed that help was on its way.
Boris Johnson’s government previously announced a raft of measures to help people cope with soaring bills - however critics argue they do not go anywhere near far enough.
Households should start receiving £400 off their energy bills from October, with the discount made in six instalments.
They also signed-off a one-off cost of living payment of £150 from September 20 for those on disability benefits.
Meanwhile, more than eight million low-income households on means-tested benefits will also receive £324 - the second instalment of a cost-of-living payment - this autumn. The first instalment of £326 was made in July.
Pensioners who receive the winter fuel payment - worth £200-£300 - will receive an additional one-off £300 in November or December.