Minato Mirai 21 (みなとみらい21, Minato Mirai Nijūichi^?), often shortened to Minato Mirai or MM is a large urban development in Yokohama, Japan. The Minato Mirai 21 area was designated to be a new urban center planned to connect Yokohama's traditional important areas of Kannai and the Yokohama Station area.

Minato Mirai 21 was originally proposed as one of Yokohama's six major development plans by the mayor of Yokohama, Ichio Asukata, in 1965. After several assessments and review sessions, actual construction started in 1983. The area where it is located was once known as Mitsubishi Heavy Industries, Ltd's Yokohama shipyard and the Japanese National Railways classification yard, Takashima wharf and Shinko wharf of Port of Yokohama. Conducted as an Urban Renewal and reclaimed land project, the port and the industrial area once divided the two city centers of Kannai and Yokohama Station, but now the area has become a new business district in Yokohama. The name Minato Mirai 21 means "Port of the Future [in] the 21[st century]", which was selected by a public opinion poll.

The area is now flourishing as one of the newest urban business districts in the Greater Tokyo Metropolitan area, symbolized by Landmark Tower, Japan's tallest skyscraper, the three Queens Square Towers, which contain a large shopping mall, the Pacifico Yokohama convention center, the Intercontinental Hotel, the Cosmo Clock 21 Ferris wheel, and more. Next to Landmark Tower is the Yokohama Museum of Art.