A report by children's charity Buttle UK, said that around one third of the families it supports each year need at least one bed for their child or children.
Given that, according to government statistics, there are 3.9m children in poverty, and there are around three children, on average, in each of the families it supports, Buttle calculates that there are approximately 1.3m families in poverty in total.
If one in three of these families needs beds, the total number of children without a bed comes to 429,000.
"These are children who do not have a suitable bed to sleep in because they are sharing with parents or siblings; they are sleeping on the floor or their beds are damaged to the point where they are simply not fit to use," Buttle chief executive Gerri McAndrew said in the charity's report, called The Real Face of Child Poverty in the UK in 2017.
"This is a staggering figure, and surely not one that is acceptable in the UK in 2017."
Analysis of grants it has provided over the past decade also revealed that lone parents account for around two thirds (63 per cent) of cases where a family in poverty has reached crisis point.
Just under half (44 per cent) of families in crisis lack basic materials, including washing machines, children's clothing as well as beds.
Over the last 10 years Buttle UK has supplied families with 18,885 washing machines, 16,564 cookers, 9,954 fridge freezers and made 5,023 grants for children's clothing.
The highest number of grants were made to cities in the North of England, Midlands and Scotland, including Sheffield, Birmingham, Leeds, Glasgow and Bradford.
In addition, requests for support spike during the summer holidays, as families do not have access to extra support in schools such as free meals.
Buttle UK estimates that every £1 handed to families through its grants saves the Treasury £6 by reducing the risk of school absence, exclusion and anti-social behavior as well as preventing accidents in the home.
Figures for 2015/16 published by the Department for Work and Pensions in March estimate that four million children are living in low-income families, after housing costs, compared with 3.9m the previous year.
This equates to 30 per cent of all UK children classed as living in poverty, after housing costs have been taken into account.
The figures also revealed that 67 per cent of children in poverty have at least one parent in work.
The Department for Work and Pensions has been contacted for comment.