The Flatiron District is a neighborhood in the New York City borough of Manhattan, named after the Flatiron Building at 23rd Street, Broadway and Fifth Avenue. Generally the Flatiron District is bounded by 20th Street, Union Square and Greenwich Village to the south; the Avenue of the Americas (Sixth Avenue) or Seventh Avenue and Chelsea to the west; 25th Street and NoMad to the north; Rose Hill to the northeast, and Lexington Avenue/Irving Place, Gramercy Park to the east.

 The Flatiron District encompasses within its boundaries the Ladies' Mile Historic District and the birthplace of Theodore Roosevelt, a National Historic Site. The Flatiron District was also the birthplace of Silicon Alley, a metonym for New York's high technology sector, which has since spread beyond the area.

The Flatiron District is part of New York City's Manhattan Community Board 5.