A council is bringing in help from other local authorities to help with its struggling children's services.
Children's services at Surrey County Council (SCC) require immediate improvement, according to Ofsted.
The watchdog found children were being "exposed to harm for too long" due to "inadequate" social services.
Council leader David Hodge said: "We fully accept there is a great deal for us to do to make sure we look after the children of Surrey."
The children's minister Nadhim Zahawi has also appointed a children's commissioner to work in the county.
Hampshire County Council will assist SCC with developing early help work, the Local Democracy Reporting Service (LDRS) said.
Essex County Council will help to review and restructure the multi-agency safeguarding hub, while Hertfordshire County Council will deploy its director of children's services to work in Surrey for two days a week to introduce a family safeguarding system.
A mental health expert will help address immediate problems with child and adolescent mental health services and a new children's academy will train all staff working with children in agencies focusing on early help, safeguarding and looked after children.
Surrey Heartlands Health and Care Partnership will lead a programme to support vulnerable children, the LDRS said.
Clare Curran, cabinet member for children's services, said: "We have brought in one of the country's most experienced and highly-regarded children's services directors, Dave Hill, to spearhead the changes we need to make."
The leader of the Conservative authority, Mr Hodge, said: "There is no doubt that report made for very difficult reading for all of us. We all take this judgement extremely seriously."
Mr Hodge, who was brought up in care, said the wellbeing of children was something he was "passionate about".
"It's really important as corporate parents we can make a difference," he said.
As of January 2018, more than 6,000 children in the county were accessing a specialist children's service.