Madison Avenue is a north-south avenue in the borough of Manhattan in New York City, United States, that carries northbound one-way traffic. It runs from Madison Square (at 23rd Street) to meet the southbound Harlem River Drive at 142nd Street, passing through Midtown, the Upper East Side (including Carnegie Hill), East Harlem, and Harlem. It is named after and arises from Madison Square, which is itself named after James Madison, the fourth President of the United States.

Madison Avenue was not part of the original Manhattan street grid established in the Commissioners' Plan of 1811, and was carved between Park Avenue (formerly Fourth) and Fifth Avenue in 1836, due to the effort of lawyer and real estate developer Samuel B. Ruggles, who had previously purchased and developed New York's Gramercy Park in 1831, and convinced the authorities to create Lexington Avenue and Irving Place between Fourth Avenue (now Park Avenue South) and Third Avenue in order to service it.

The street's name has been metonymous with the American advertising industry since the 1920s. Thus, the term "Madison Avenue" refers specifically to the agencies and methodology of advertising. "Madison Avenue techniques" refers, according to William Safire, to the "gimmicky, slick use of the communications media to play on emotions."