Ofsted noted the troubled authority has seen a decline in the quality of its support for young people since the last full inspection in 2016 and gave the service an ‘inadequate’ rating.
Since the last Ofsted inspection the council has taken the unprecedented step of issuing two Section 114 orders, banning all non-statutory spending, though its finances have improved since.
The education watchdog’s report, published Monday, highlighted a “range of significant weaknesses in services whose effectiveness is central to protecting children”.
It added: “Northamptonshire’s children’s services are failing to keep children safe”.
The inspection, conducted in late June, found that children in care were living in unregulated and unsafe places, and some care leavers were vulnerable and homeless.
Lead inspector Paul Higham said after a period of “significant instability at senior leadership level” the new senior management team has made some important improvements.
Director of children’s services Sally Hodges said: “We accept the findings of this Ofsted inspection report entirely.
“We recognise the failings that inspectors have highlighted and equally have a determination to build on the signs of progress they have identified.”
Cabinet member for children services Fiona Baker said: “It is regrettable that our services overall have been graded as inadequate but it is a grading we agree with and we are determined to tackle the weaknesses identified.
“It is clear from this report that we increasingly have the determination, plans and leadership in place to begin to make real and lasting improvements.”
A Department for Education spokesperson said: “We will not hesitate to take action where children’s services are failing vulnerable children and young people.
“The latest Ofsted inadequate rating underlines the importance of swift action to raise standards and ensure the welfare and protection of children in the region.”
The council came under fire earlier this year after two children the county deemed “unlikely to suffer harm” were murdered by people caring for them