Ōta is a special ward in the Tokyo Metropolis in Japan. The ward refers to itself in English as Ōta City. It was formed in 1947 as a merger of Ōmori and Kamata following Tokyo City's transformation into Tokyo Metropolis. The southernmost of the 23 special wards, Ōta borders the special wards of Shinagawa, Meguro and Setagaya to the north, and Kōtō to the east. Across the Tama River in Kanagawa Prefecture is the city of Kawasaki, forming the boundaries to the south and west.

Special wards are a special form of municipalities in Japan under the 1947 Local Autonomy Law. They are city-level wards: primary subdivisions of a prefecture with municipal autonomy largely comparable to other forms of municipalities.