The charity said the number of homeless families in Britain has been "rising steadily over recent months" and the number of families with children forced to live in B&Bs has also increased by 57% over the past year.
Shelter's helpline and local advice centres helped more than 1,000 people at risk of becoming homeless over the festive period last year and now the charity is launching an emergency Christmas appeal for public support.
Campbell Robb, chief executive of Shelter, said: "It's easy to think of homelessness as single people sleeping rough. What people don't often consider is the rising numbers of families who, through no fault of their own, have lost their home and have no permanent roof over their heads. For people with children, 'sofa surfing' with friends and family often just isn't a realistic option."
He said the main triggers for homelessness include relationship breakdowns, job losses and landlords ending renters' tenancies.
He added: "No child should be homeless at Christmas. Every December, Shelter's helpline and advice centres deal with thousands of people at risk of losing their home. We need everyone's support in the coming months so our advisers can help prevent families from becoming homeless, and help them into a home if the worst should happen," he said.
A spokesman from the Department for Communities and Local Government said: "This country has one of the strongest homelessness safety nets in the world and the bigger picture is that homelessness is actually lower than for 28 of the last 30 years.
"But there is always more that can be done. That's why we have recently set out a cross-Government approach to ensuring that anyone at risk of homelessness gets help at the earliest possible stage to prevent them from losing their home.
"The Government is also investing £400 million in homelessness prevention over four years, and last year provided an additional £70 million."
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