The UN also called on advertisers, media organisations and researchers to prioritise children’s safety and participation in shaping digital policies.
It said young people increasingly faced disinformation, online harassment, algorithmic bias and the malicious use of Artificial Intelligence.
The warning was contained in a new UN brief released ahead of International Youth Day.
According to the report, more than eight in 10 young people aged between 15 and 24 worldwide are now online.
It said internet use among young people in low-income countries was almost twice that of the general population.
UN Secretary-General António Guterres had earlier called for an AI Child Safety Pledge to strengthen protection for children.
Guterres compared emerging artificial intelligence systems to untested medicine, warning against exposing children to poorly regulated technologies.
“No child should be a guinea pig for unregulated AI,” Guterres said adding, “When a child is harmed, the answer must never be ‘the algorithm did it”.
The UN brief said many online harms affecting children were not accidental but partly to business models designed to monetise attention, personal data, engagement and online spending.
The report identified algorithms encouraging prolonged use and manipulative digital designs among the major risks confronting young people.
It also highlighted “dark patterns”, loot boxes and other techniques capable of encouraging compulsive online behaviour.
The UN warned that children were particularly vulnerable because their habits, identities and relationships were still developing.
The risks include AI-generated harmful content and the use of artificial intelligence to facilitate exploitation.
The report also raised concern about increasingly hidden advertising techniques targeting children and encouraging online spending.
“Taken together, these practices normalise pervasive commercial surveillance and manipulative design,” the brief said.
It added that children were being exposed during some of the most impressionable years of their development.
The UN, however, stressed that children and young people should not be viewed only as victims of online risks.
It described them as creators, organisers, journalists, advocates and participants in public debate.
The report said youth-led movements continued to influence civic life and public conversations across different societies.
However, it warned that online spaces could also expose young organisers to harassment, intimidation and surveillance.
The UN, therefore, urged governments and researchers to include young people in policymaking on information integrity.
Charlotte Scaddan, UN Senior Adviser on Information Integrity, said children could contribute significantly to solving the digital information crisis.
“Protecting them and including them are not competing goals. We have to do both,” Scaddan said.
The report proposed legal and policy measures for Member States to strengthen online child protection.
It also urged technology companies to design platforms with stronger child-safety safeguards.
Advertisers were advised to respect children’s rights and avoid exploitative commercial practices.
The UN also called on news organisations to better serve young audiences and promote reliable information.