Moscow Time (MSK; Russian: моско́вское вре́мя, romanized: moskovskoye vremya) is the time zone for the city of Moscow, Russia, and most of western Russia, including Saint Petersburg. It is the second-westernmost of the eleven time zones of Russia, after the non-continguous Kaliningrad enclave. It has been set to UTC+03:00 without DST since 26 October 2014;^[1] before that date it had been set to UTC+04:00 year-round on 27 March 2011.^[2]

Moscow Time is used to schedule trains, ships, etc. throughout Russia, but air transport in Russia is scheduled using local time. Time in Russia is often announced throughout the country's other timezones on radio stations as Moscow Time, which is also registered in telegrams, etc. Descriptions of time zones in Russia are often based on Moscow Time rather than UTC; for example, Yakutsk (UTC+09:00) is said to be MSK+6 in Russia.

Until the October Revolution, the official time in Moscow corresponded to GMT+02:30:17 (according to the longitude of the Astronomical Observatory of Moscow State University). In 1919 the Council of People's Commissars of the RSFSR introduced the system of time zones in the country, and Moscow was assigned to the second administrative time zone, equal to GMT+02:00. Other zones east of the 37.5° meridian to Arkhangelsk, Vologda, Yaroslavl, Kostroma, Ivanovo, Vladimir, Ryazan, Tula, Lipetsk, Voronezh and Rostov-on-Don were also included in the second belt.

In accordance with the 16 June 1930 Decree of the Council of People's Commissars, the Decree Time was introduced by adding one hour to the time in each time zone of the USSR, so that Moscow Time became three hours ahead of Universal Time.^{[citation needed]}

Until 2011, during the winter, between the last Sunday of October and the last Sunday of March, Moscow Standard Time (MSK, МСК) was three hours ahead of UTC, or UTC+03:00. In the summer, Moscow Time shifted forward an additional hour ahead of Moscow Standard Time to become Moscow Summer Time (MSD), making it UTC+04:00.

In 2011, the Russian government proclaimed that daylight saving time would be observed all year round, thus effectively displacing standard time — claiming health concerns attributed to the annual shift to-and-fro DST.^[1] On 27 March 2011, Muscovites set their clocks forward for a final time, effectively observing MSD, or UTC+04:00, permanently.

On 29 March 2014, after the annexation of Crimea by the Russian Federation, the Republic of Crimea and the city of Sevastopol — two federal subjects established by Russia on the Crimean Peninsula — switched their time to MSK on 30 March 2014 (from UTC+02:00 with DST to UTC+04:00 with permanent DST).

On 1 July 2014, the State Duma passed a bill partially repealing the 2011 change, removing permanent DST and putting Moscow Time from 26 October 2014 on permanent UTC+03:00 and thus back to standard time.

Most of the European part of Russia (west of the Ural Mountains) uses Moscow Time. Kaliningrad Oblast uses Kaliningrad Time (UTC+02:00). Samara Oblast and Udmurtia use Samara time (UTC+04:00) and Perm Krai, Bashkortostan and Orenburg Oblast use Yekaterinburg time (UTC+05:00). Since 2014, Moscow Time has been observed in Crimea after it was annexed and in Russian-occupied territories of Ukraine, including after their declared annexation in 2022.^[3]

Since political, in addition to purely geographical, criteria are used in drawing time zones, they do not precisely adhere to meridian lines. The "purely geographical" MSK (UTC+03:00) time zone would consist of the band between meridians 37°30' E and 52°30' E. However, there are European locales that despite lying in an area with a "physical" UTC+03:00 time, are in another time zone; likewise, there are European areas that have gone for UTC+03:00, even though their "physical" time zone is different. Following is a list of such anomalies:

• East Africa Time, also in UTC+03:00
• Time in Russia