The ContactPoint system will list all 11 million children in England, including their names, addresses, schools, GPs and whether they are receiving help from social services.
If parents or children give their consent, it could also include more sensitive information about whether children have accessed sexual or mental health services or had treatment for substance abuse.
The database will make it easier to share information and is designed to stop 3 to 18-year-olds falling between different services, as happened to Victoria Climbie, a victim of child abuse who died.
But vulnerable children have said they are worried about information falling into the wrong hands. Sixty-two children who live away from home or receive social care answered a survey or were consulted.
Roger Morgan, Children's Rights Director for England, said: "The children have told me that they are concerned about the safety of ContactPoint. They want to be assured that their information will remain safe and confidential and have asked specifically that the Government will never put a child's photograph or telephone number on the database. There will always be a need to keep security under review, as the repercussions of information falling into the wrong hands could be extremely dangerous."
The surveyed children were very concerned that paedophiles might try to access their details, the report said. They feared the system's security would be breached or its information shared inappropriately.
There was also concern that it would not contain data about those most at risk, such as runaways or the children of asylum-seekers.
ContactPoint will not contain specific information about the services children access, but should alert people if other organisations are working with the same child. It will be available to around 333,000 vetted users, including heads, GPs and social and youth workers.
Kevin Brennan, the Children's Minister, said children's concerns had already been addressed. "I think we should also bear in mind that other children have told us they are glad that ContactPoint is being brought in," he said.