The Flatiron District is a small 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 can be said to be bounded by 20th Street, Union Square and Greenwich Village to the south; Sixth 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 and the neighborhood of Gramercy to the east.

Broadway cuts through the middle of the district, and Madison Avenue begins at 23rd Street and runs north. At the north (uptown) end of the district is Madison Square Park, which was completely renovated in 2001. The Flatiron District encompasses within its boundaries the Ladies' Mile Historic District and the birthplace of Theodore Roosevelt, a National Historic Site.

Baruch College of the City University of New York, is located on E. 23rd Street and Lexington Avenue on the eastern edge of the district. The College sits on the former site of the Free Academy (now City College of New York), which was founded in 1847 and was the first institution of free public higher education in the United States. Baruch's Newman Vertical Campus as well as the Zicklin School of Business, the largest collegiate school of business in the United States, are also located on 24th and 25th Streets between Third and Lexington Avenues.