Ofsted's data also shows that the number of councils found to be inadequate in all children's services overall has also risen from none last year to four this year.
Those councils were Doncaster, Haringey, Milton Keynes and Surrey.
The number of councils which provide good or outstanding children's services has also fallen from 78% to 73%.
'Most vulnerable'
In a statement, Ofsted said the increase in inadequate ratings was "a cause for concern".
Chief inspector Christine Gilbert said although there had been "significant achievements", she was concerned that some services remained inadequate.
She said: "Where this has been found, we have clearly identified where improvements are needed.
"We would expect those working in children's services to address these issues as an urgent priority with support from their local government office.
"We will be inspecting next year to ensure they make good progress."
Three councils were rated outstanding for all children's services - Gateshead, Kensington and Chelsea, and York.
Mr Balls said that in all nine of the authorities judged to be inadequate the government had either already intervened or would now do so now.
"Following initial discussions we will then decide what further action or support is required," he said.
"In all cases we will work with the authorities concerned - and with the Local Government Association - to put in place improvement support or intervention as quickly as possible."
Earlier this month, MPs called for Ofsted to review its procedures, after it emerged that inspectors had made "favourable" inspections of Haringey Council shortly after Baby P died.
He suffered months of abuse while on the council's child protection register.
A more thorough inspection this year revealed gross inadequacies in Haringey Council's child protection service.
During a question session with MPs, Ms Gilbert admitted the inspection in 2007 was misleading because, she argued, her inspectors had been misled by Haringey's data.
Ofsted said it would introduce a new inspection system from next year.
The so-called Comprehensive Area Assessment promises to "ensure a stronger focus on front-line practice, including annual unannounced inspection visits in every local authority".
Christine Gilbert appeared before the select committee last week
But despite these assurances, the Commons Children, Schools and Families Select Committee is still planning to investigate the inspectorate.
Chairman Barry Sheerman accused Ms Gilbert of being "complacent" and rejecting "out of hand" the committee's suggestions.
"I put it to her�. why didn't she embed, immediately, an inspector in each of them so that there was actually a real human being there, looking people in the eye, going out with young social workers on their difficult visits," he said.
Mr Sheerman said inspectors were trying to juggle responsibility for monitoring schools, nurseries and child protection.
"I think very often they are taking the kind of inspection system that is probably alright, but not wonderful, for schools across to children's services and it doesn't work," he added.
'Being rectified'
Lorna Reith, cabinet member for children and young people at Haringey, said significant changes would be needed "to restore confidence in child protection".
They need better training and support to manage the high levels of stress
Helga Pile, Unison
"Those changes have already begun. They are being driven by new political and managerial leadership," she said.
A spokeswoman for Essex County Council said "areas of weakness" were being "rectified".
West Sussex County Council also said "significant improvements" had been made since Ofsted carried out its assessment.
Helga Pile, from public sector union Unison, said its members working in social care were "struggling with huge caseloads, high turnover rates of staff and massive amount of paperwork".
"They also need better training and support to manage the high levels of stress associated with making tough decisions on the safety of children day in, day out," she said.
Ofsted inspected 150 councils, but three are still contesting their grades.
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