Ninth Avenue or 9 Av may refer to:
Roads Ninth Avenue (Manhattan), New York City Ninth Avenue (Islamabad), Islamabad, Pakistan
Subway/Transit stations Ninth Avenue (BMT West End Line), a subway station in Brooklyn Irving and 8th Avenue / 9th Avenue and Irving stations
Transit lines IRT Ninth Avenue Line
Other uses 9 Av, the ninth day of Av, the fifth month of the Hebrew calendar Tisha B'Av a day of fasting in Judaism observed on 9 Av