Councillor Bob Badham today stood down from his post of cabinet member for children and families in Sandwell in the wake of the report which rated the council's arrangements for protecting children as inadequate.
The Government watchdog said the authority has "systematic failures" in arrangements for the protection of children and the inspection uncovered failings in overall effectiveness, help and protection for young people, quality of practice, and leadership and governance.
Council chiefs have pledged improvements, while council leader Councillor Darren Cooper said he was "devastated" with the rating.
Councillor Badham said: "As the cabinet member I have final responsibility for ensuring children's services are fit for purpose. The Ofsted report has made it clear they are not and therefore I have decided to resign with immediate effect.
"I was fully aware of problems and knew we had to take radical action. I am proud we were the first council in the country to bring in outside experts on a contract to help us make improvements. Ofsted inspections these days are a lot tougher. I have done the job for the three years and think children's services are in the right place to improve. However, it now needs new leadership to get it to where it should be."
Councillor Cooper today paid tribute to Councillor Badham for leading children's services over the last three years. He said: "Bob has worked tirelessly. However, I appreciate and understand his position in resigning."
The resignation of Councillor Badham comes as it emerged council worker Helen Smith, who was suspended from her role as service director for children and families ahead of the publication of the report, has also resigned from the authority.