Metrorail is a rapid transit system in Miami and Miami-Dade County in the U.S. state of Florida. Metrorail is operated by Miami-Dade Transit (MDT), a departmental agency of Miami-Dade County. Opened in 1984, it is Florida's only rapid transit metro system, and is currently composed of two lines of 23 stations on 24.4 miles (39.3 km) of standard gauge track. Metrorail serves the urban core of Miami, connecting Miami International Airport, the Health District, Downtown Miami, and Brickell with the northern developed neighborhoods of Hialeah and Medley to the northwest, and to suburban The Roads, Coconut Grove, Coral Gables, and South Miami, ending at urban Dadeland in Kendall. Metrorail connects to the Metromover in Downtown, which provides metro service to the entirety of Downtown and Brickell. Additionally, it connects to South Florida's commuter rail system at Tri-Rail station, as well as Metrobus routes at all stations. In 2023, the system had 13,439,300 rides, and about 48,300 per day in the fourth quarter of 2023.

Rapid transit or mass rapid transit (MRT), also known as metro, is a type of high-capacity public transport that is generally built in urban areas. A rapid transit system that primarily or traditionally runs below the surface may be called a subway, tube, or underground. Unlike buses or trams, rapid transit systems are railways, usually electric, that operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles. They are often grade-separated in tunnels or on elevated railways.