Children today have many opportunities to access modern technology, especially artificial intelligence (AI), which helps support their right to access information and education. However, some AI applications may collect and process children's personal data, posing risks of privacy violations if not strictly controlled. Many countries, including Vietnam, have issued regulations on protecting privacy and personal data, but limitations remain in addressing the challenges posed by AI. Ensuring the right to privacy of children in the context of digital transformation requires an approach that balances the benefits of digital technology with the best interests of the child. This study employs the method of normative legal analysis to examine the legal systems of the United States (U.S.) and the European Union (EU) and subsequently uses comparative legal analysis to propose solutions for improving Vietnamese law in protecting the privacy and personal data of children in the AI era.