The admission of warrantless searches during national-security investigations is likely to stoke privacy concerns in Congress.
The figure was published in an annual report by the Office of the Director of National Intelligence, according to the Wall Street Journal.
It disclosed that the FBI conducted searches on data that had previously been collected by the National Security Agency.
It marks the first time a US intelligence agency has attempted to publish such an accounting record.
More than half of the searches were related to identifying and protecting potential victims of alleged Russian hackers trying to break into critical infrastructure.
The intelligence agency has repeatedly faced scrutiny for its oversight of how authorities use the data, including admonishment from the Foreign Intelligence Surveillance Court in 2018 that found violations of the constitutional privacy rights of Americans.