One in seven Britons has turned to credit such as a payday loan or unauthorised overdraft to help cover their rent or mortgage in the last year.
Shelter, who carried out the research, has warned that relying on such methods could lead to people losing their homes.
The figure equates to almost seven million people when projected on a national scale, the charity said.
And it has urged those sinking into a "spiral of debt" to seek immediate help.
Shelter found that 2% of people have used at least one payday loan to fund their rent or mortgage in the last year, equating to almost one million people nationally.
It said such loans, which are intended for short-term use and can charge as much as 4,000% APR in some cases, are an "unsustainable" way of paying for housing.
Campbell Robb, chief executive of Shelter, said: "These shocking findings show the extent to which millions of households across the country are desperately struggling to keep their home.
"Turning to short-term payday loans to help pay for the cost of housing is totally unsustainable. It can quickly lead to debts snowballing out of control and can lead to eviction or repossession and ultimately homelessness."
The Shelter report will fuel concerns about people seeking high-interest credit, following a report from insolvency trade body R3 last month which predicted payday loan companies will see a surge in demand in the coming months as Britons struggle with their finances.
The Office of Fair Trading is planning a review to ensure businesses are complying with responsible lending rules amid criticism of the payday loan sector.
The Consumer Finance Association (CFA), which represents businesses offering short-term loans, stresses on its website that payday loans are designed to be repaid typically within a month and a half and they are not appropriate if a large sum of cash is needed to be paid back over months or years.
Martin Lewis of MoneySavingExpert.com said: "It's incredibly worrying there's now evidence of people using payday loans to meet housing costs.
"While it's an obvious temptation to grasp these loans as a lifeline, in the long run it may hurt more than help."