The legislation received formal approval from the Queen yesterday when parliamentary business was officially wrapped up prior to dissolution of parliament next week ahead of June's general election.
Provisions within the Children and Social Work Act will lead to a new system of regulation for social workers, change the factors courts and practitioners consider when making decisions on adoptions, and establish a panel to identify serious child safeguarding cases that require review.
It will also require local authorities to provide personal advisers to care leavers up to the age of 25. Meanwhile sex and relationship education (SRE) will be made compulsory in all secondary schools.
Speaking in parliament about the bill, children's minister Edward Timpson said: "This bill represents an important step forward for vulnerable children. It defines what good corporate parenting looks like, and secures the involvement of the whole council in looking out for children in care or leaving care.
"It requires every local area to set out exactly what support they are offering to care leavers, making it easier for young people to access support. It extends the help of a personal adviser to all care leavers up to the age of 25.
"It introduces improved national arrangements for analysing serious incidents and learning from them, and strengthened arrangements for local multi-agency co-ordination of safeguarding. It extends educational support to children leaving care via adoption or special guardianship. It creates the conditions for good placement decisions to be made for children coming into the care system.
"It introduces a new, bespoke regulator for social work that will be empowered to raise standards in social work and raise the status of this vital profession. It also paves the way for a new system of assessment and accreditation, which will give social workers opportunities to develop and progress in their profession."
One of the major elements of the legislation - placing sex and relationship education on a statutory footing, was a late addition to the bill following pressure from campaigners and MPs.
The government previously blocked an attempt by Labour to introduce compulsory SRE through an amendment to the Children and Social Work Bill.
The government also bowed to pressure and ditched a highly controversial element of the bill - the so-called "exemption" clause, that allows councils to apply for exemptions from social care legislation.
The Children and Social Work Bill was one of 22 bills to receive Royal Assent yesterday.