The highest number of homeless children in a decade were recorded this year, according to charity Shelter.
Some 128,000 will be living in temporary accommodation on Christmas day.
At least 140 families become homeless every day, the report said, and 61% of families helped by Shelter's frontline services were homeless or on the brink of losing their home.
The new report, based on in-depth interviews with children and their families living in emergency B&Bs and hostels, reveals the extent of the homelessness crisis.
Every family the charity spoke to was living in a single room and a quarter had no access to a kitchen. Half were forced to share toilet and bathroom facilities with other households and more than a third of parents had to share a bed with their children.
In England, where the highest number of families are placed into B&Bs, 45% stay beyond the six-week legal limit. The charity found this had a negative impact on the children's mental and physical well-being.
The chief executive of Shelter, Polly Neate, said: ‘It's a national scandal that the number of homeless children in Britain has risen every year for the last decade,'
Responding to the report, Cllr Judith Blake, the Local Government Association's (LGA) housing spokesperson, said: ‘On average, councils are having to house the equivalent of an extra secondary school's worth of homeless children in temporary accommodation every month.
‘It's clear the current situation is unsustainable for councils, and disruptive for families.
‘While the Government's indication that it will explore ways to enable councils to build more homes is encouraging, these new homes can't appear overnight, and the demand is urgent.
‘Councils are determined to tackle homelessness, but we now need Government to support this local effort.'
Cllr Blake said the Government could support councils by adapting welfare reforms to ensure housing remains affordable for low-income families.
She added that Whitehall should allow councils to borrow to build new homes as part of the upcoming local government finance settlement.
