In a ruling on Thursday, Judge Bryan Biedcheid said the bulk of the money — $US420 million ($A597 million) — will be used for treatment services for young people.
The rest will go toward awareness and prevention, screening services and other costs over the next five years.
In the first phase, jurors had ordered $US375 million ($A533 million) in civil penalties against Meta, determining that it knowingly harmed children's mental health and concealed what it knew about child sexual exploitation on its platforms.
In the second phase, prosecutors had asked the judge to impose fundamental changes at Meta aimed at reining in addictive features, improving age verification and preventing child sexual exploitation through default privacy settings and closer oversight.
The court said federal children's privacy laws prevent Meta from applying age-verification tools to children under 13.
The Children's Online Privacy Act, or COPPA, means it cannot order Meta to request children to submit personal data or be passively tracked online, even for age verification purposes.
The court also noted that ordering Meta to verify children's ages for only Meta and not other social media companies would be "inequitable and unduly injurious" to the company.
The Associated Press has reached out to New Mexico's Department of Justice and Meta for comment on the decision.
