Older teens are more at risk of abuse and neglect than any other age group, according to new research from the Children's Society.
The report also shows that four in five UK parents think neglect and abuse laws should be changed to include 16- and 17-year-olds.
The report comes in advance of a House of Commons debate on Monday on abuse and neglect legislation in the Serious Crime Bill.
Teenagers aged 16 and 17 who live in England are more likely to be abused or neglected than any other age group, but are given the least protection, according to the analysis.
Almost 25,000 teenagers aged 16 and 17, the equivalent of one in 50, are at risk of abuse or neglect. They may suffer emotional, physical or sexual abuse or their caregiver may fail to provide them with medical help, adequate food or clothing.
Existing child cruelty laws allow prosecutions to be brought for neglect, ill treatment and abandonment but only until the child is aged 15.
The Children's Society is calling on the Government to make changes to the Serious Crime Bill, which includes changes to the law on child abuse and neglect.
Currently in law, only children under the age of 16 can be victims of child cruelty and neglect, unless they are in care.
With education or training compulsory until the age of 18, most teenagers live at home and are dependent on their families for emotional and financial support, leaving them open to abuse and neglect. And compared to younger children, they have greater freedom but lack the life experience of adults which makes them a target for predatory adults who may sexually exploit them or involve them in crime, the Children' Society says.
The Children's Society is calling for Child Abduction Warning Notices, used by police to disrupt the contact between children and harmful adults like drug dealers or sexual predators, to be applicable to 16 and 17-year-olds. Currently, they can only be used to protect vulnerable children aged 15 and under, unless they are in local authority care. It is also calling for child cruelty and neglect laws to apply to 16 and 17-year-olds.
Lily Caprani of The Children's Society said: "It is nonsensical that children aged 16 and 17 are at most risk of abuse and neglect, and yet aren't given the same legal protection as younger children. Victims of cruelty and abuse can experience devastating mental and physical harm that can blight the rest of their lives. In the eyes of the law, they are children until they are 18 yet the law does not sufficiently protected from abuse and cruelty.
"We are urgently calling on the Government make it a criminal offence for a parent or guardian to abuse or neglect any 16- or 17-year-old who lives with them, and for Child Abduction Warning Notices to apply to 16- and 17-year-olds.
"Time is running out. This is the Government's last chance before the election to protect vulnerable 16- and 17-year-olds from abuse and neglect and keep them safe."
The report says there are a number of reasons for the high numbers of older teens "in need".
It says: "From our practice we know that those young people aged 16-17 who seek help often have been known to services through their earlier adolescent years but did not receive effective safeguarding response.
"As a result the issues in their lives escalate to such an extent that a planned intervention from children's services is needed."
