The total number of households that foster children rose to more than 50,000 last year, but 13 per cent of the workforce retire or leave the profession annually.
On any one day, there is now a record 61,700 children living with foster families. But the number of children in care has increased for a sixth year in a row.
This means an extra 7,350 foster families are needed in England, 850 in Scotland, 600 in Wales and 200 in Northern Ireland, this year alone.
The Fostering Network is calling on more people to consider fostering, to prevent children being placed far from their local area.
Robert Tapsfield, chief executive of the Fostering Network, said: “Despite fostering services attracting more people to become foster carers, the continuing rise of children coming into care means thousands more are still needed this year alone.
“In particular we know that fostering services are looking for foster carers to offer homes to teenagers, children with disabilities and sibling groups.
“These children need a stable family life to help them grow and achieve their potential. By becoming a foster carer people can help them have the best possible opportunity for a positive future, to do well at school and be successful in later life.”
Debbie Jones, president of the Association of Directors of Children's Services (ADCS), said councils are working with the government and other partners to make sure that foster families get the right support and guidance.
“Several factors have led to the number of children needing foster families increasing over a number of years,” she said.
“For some children fostering will be a short-term solution to a specific problem, other children will be in foster care for much longer.
“We know that foster carers are absolutely invaluable and provide loving and stable placements to some of our most vulnerable children and many find fostering a rewarding endeavour.”