The government is also planning a register of one in four adults
A child protection database containing the contact details for all under 18-year-olds in England will be accessible to 390,000 staff, say ministers.
The ContactPoint database is intended to improve information sharing between professionals working with children.
Children's Minister Baroness Morgan said parents would not be allowed to remove their children from the list.
The Conservatives attacked the £224m database as "another expensive data disaster waiting to happen".
The Liberal Democrats have also previously opposed what they called an "intrusive and expensive project".
Children's Minister in the House of Commons, Beverley Hughes, said the database would allow people working with children to "put their particular piece of the jigsaw into the whole picture".
The database was created as a result of the inquiry that followed the death of eight-year-old Victoria Climbie in 2000. But it has experienced a series of technical delays.
The latest stage of the project is that 17 local authorities will begin training staff in how to use the database, which will hold the name, address, parents' contact details, date of birth, school and doctor of every child in England.
Each child will also have a unique identifying number.
The setting up of the database is intended to improve the co-ordination between different professionals working with children.
For instance, it will allow education authorities to know if a child has come to the attention of social services or health workers.
Among those who will be able to see the information will be local authorities, police, health services and children's charities.
But Baroness Morgan says that there will be provision for "shielding" the details of young people facing risk if they were identified.
"For someone fleeing domestic violence for example it is important we make sure the ContactPoint directory can shield in some way," she said.
The Conservatives' children's spokesman, Tim Loughton, challenged the value of such a database.
"Which do you think is more likely to protect vulnerable children - investing in more permanent and appropriately trained social workers and reducing their caseload or instead throwing money at another expensive data disaster waiting to happen?"
The government is also planning to set up another major child protection register for adults who work with young people.
The Independent Safeguarding Authority, set to begin work later this year, plans to have a register of more than 11 million adults - representing about one in four of the adult population of England.