The Moscow Metro is a rapid transit system in the Moscow Oblast of Russia. It serves the capital city of Moscow and the neighbouring cities of Krasnogorsk, Reutov, Lyubertsy, and Kotelniki. Opened in 1935 with one 11-kilometre (6.8 mi) line and 13 stations, it was the first underground railway system in the Soviet Union.

As of December 2024, the Moscow Metro has 271 stations and 466.62 km (289.94 mi) of route length, excluding light rail Monorail, making it the 8th-longest in the world, the longest in Europe and the longest outside China. It is also the only system in Russia with two circle lines. The system is mostly underground, with the deepest section 73 m (240 ft) underground at the Park Pobedy station, one of the world's deepest underground stations. It is the busiest metro system in Europe, the busiest in the world outside Asia, and is considered a tourist attraction in itself, thanks to its lavish interior decoration.

The Moscow Metro is a world leader in the frequency of train traffic, as intervals during peak hours often do not exceed 90 seconds. In February 2023, Moscow was the first in the world to reduce the intervals of metro trains to 80 seconds, but in practice trains are not likely to exceed the 90 seconds interval.