National Security Act

National Security Act may refer to:
 * National Security Act (India), law to provide for preventive detention
 * National Security Act (South Korea), regarding seditious activities
 * National Security Act of 1947, a United States law that established the Central Intelligence Agency
 * National Security Act 2017 (Canada)
 * National Security Act 2023, a UK act strengthening laws against espionage, political interference, sabotage, and assassination