The Office of Naval Intelligence (ONI) was established in the United States Navy in 1882. ONI was established to "seek out and report" on the advancements in other nations' navies.

ONI's position as the naval intelligence arm began in earnest when the United States declared war on Spain in 1898 in response to the sinking of the U.S. battleship Maine in the harbor of Spanish-controlled Havana, Cuba. ONI's powers grew as it became responsible for the "protection of Navy Personnel, censorship and the ferreting out of spies and saboteurs."

In 1929 the Chief of Naval Operations made these functions the permanent duties of ONI. During World War II, Naval Intelligence became responsible for the translation, evaluation and dissemination of intercepted Japanese communications, and its budget and staff grew significantly. While other parts of the Navy were downsized after the war, Fleet Admiral Nimitz ensured ONI's continued strength, which was to prove important during the Cold War.

The Office of Naval Intelligence is the oldest continuously operating intelligence service in the United States. ONI headquarters are at the National Maritime Intelligence Center (NMIC) in Suitland, Maryland.