The Bucharest Metro (Romanian: Metroul din București) is an underground rapid transit system that serves Bucharest, the capital of Romania. It first opened for service on 16 November 1979. The network is run by Metrorex. One of two parts of the larger Bucharest public transport network, Metrorex had an annual ridership of 142,783,000 passengers during 2023, compared to over a billion annual passengers on Bucharest's STB transit system. In total, the Metrorex system is 80.1 kilometres (49.8 mi) long and has 64 stations.

The Bucharest Metro has five lines (M1, M2, M3, M4, and M5). The newest metro line, M5, was opened in 2020. A sixth metro line, M6 line, is currently under construction.

As of 2024, Bucharest Metro is the only metro system in Romania; with a second one, the Cluj-Napoca Metro, being under construction.

Bucharest Metro is part of the Bucharest public transport network which also includes STB, which operates a complex network of buses, trolleybuses, light rail and trams. STB is Bucharest's surface public network system, while Bucharest Metro operates underground (a short stretch between Dimitrie Leonida and Tudor Arghezi metro stations is the only portion of the Bucharest Metro that does not run underground). Until relatively recently, car ownership in Romania was not common: during the first part of the 20th century few people had cars, and the subsequent communist regime installed after World War II restricted personal car use. The public transportation system in Bucharest has its origin in the 19th century, with the city introducing horse-drawn trams in 1872.

The first proposals for a metro system in Bucharest were made in the early part of the 20th century, by the Romanian engineers Dimitrie Leonida and Elie Radu.

The earliest plans for a Bucharest Metro were drafted in the late 1930s, alongside the general plans for urban modernization of the city. The outbreak of World War II, followed by periods of political tensions culminating with the installation of communism, put an end to the plans.

By 1970, the public transport system (ITB) was no longer adequate due to the fast pace of urban development, although the system was the fourth-largest in Europe. A commission was set up, and its conclusion pointed to the necessity of an underground transit system that would become the Bucharest Metro. The plan for the first line was approved on 25 November 1974 as part of the next five-year plan and the construction on the new metro system started on 20 September 1975.

The network was not built in the same style as other Eastern European systems. Firstly, the design of the stations on the initial lines was simple, clean-cut modern, with most stations being relatively austere, without excessive additions such as mosaics, awkward lighting sources or elaborate and ornate decoration. The main function of the stations was speed of transit and practicality. Secondly, the trainsets themselves were all constructed in Romania and did not follow the Eastern European style of construction. Each station usually followed a colour theme (generally white – in Unirii 2 (Union 2), Victoriei 1 (Victory 1), Lujerului; but also light blue – in Obor, Universitate (University), and Gara de Nord (North Train Station); orange – in Tineretului (Of Youth Station); green – in Grozăvești), and an open plan. No station was made to look exactly like any other. Despite this, many stations are rather dark, due to the policies of energy economy in the late 1980s, with later modernisations doing little to fix this problem.