Polotsk or Polatsk is a town in Vitebsk Region, Belarus. It is situated on the Dvina River and serves as the administrative center of Polotsk District. Polotsk is served by Polotsk Airport and Borovitsy air base. As of 2025, it has a population of 79,285.

The name may be derived from the Polota River (from Russian boloto, lit. 'marsh'), which flows into the neighboring Western Dvina, or the Polochans, a tribe. The Vikings rendered that name as Palteskja. It is also called Paltesjuborg in the Norse sagas.

Polotsk is one of the earliest mentioned cities of the Eastern Slavs. The Primary Chronicle mentioned Polotsk in the year 862 (as Полотескъ, /poloteskŭ/), together with Murom and Belozersk. However, an archaeological expedition from the Institute of History of the National Academy of Sciences of Belarus suggests that Polotsk existed in the first half of the 9th century.

The first known prince of Polotsk was Rogvolod (ruled 945–978). He had two sons and a daughter named Rogneda. Rogvolod promised Rogneda to the prince of Kiev, Yaropolk, as a wife. But Yaropolk's brother, Vladimir, had attacked Polotsk before Yaropolk came. He killed Rogvolod, his wife and sons, and married Rogneda.

Vladimir and Rogneda had five children and the eldest of them, Izyaslav, became Prince of Polotsk (ruled 989–1001).

Between the 10th and 12th centuries, the Principality of Polotsk emerged as the dominant center of power in what is now Belarusian territory, with a lesser role played by the Principality of Turov to the south. It repeatedly asserted its sovereignty in relation to other centers of Kievan Rus', becoming a political capital, the episcopal see and the controller of vassal territories among Balts in the west. Its most powerful ruler was Prince Vseslav of Polotsk, who reigned from 1044 to 1101. A 12th-century inscription commissioned by Vseslav's son Boris may still be seen on a huge boulder installed near St. Sophia Cathedral.

During the Mongol invasion, Polotsk avoided being invaded or paying tribute to the Golden Horde. But in 1240, it became a vassal of the Lithuanian princes. The Grand Duke of Lithuania Vytenis annexed the city by military force in 1307, completing the process which the Lithuanian princes had begun in the 1250s. Polotsk received a charter of autonomy guaranteeing that the grand dukes "will not introduce new, nor destroy the old". It was the earliest to be so incorporated into the Grand Duchy of Lithuania. By doing so, the Lithuanians managed to firmly grasp the Dvina trade route in their hands, securing an important element for the surrounding economies. Magdeburg law was adopted in 1498. Polotsk functioned as a capital of the Połock Voivodship of the Polish–Lithuanian Commonwealth until 1772. Captured by the Russian army of Ivan the Terrible in 1563, it was returned to the Grand Duchy of Lithuania just 15 years later. It was again captured by Russia on 17 June 1654, but recaptured by Poland–Lithuania on 30 October 1660 during the Russo-Polish War (1654–67).

In 1772, Russia seized Polotsk (then Połock) as part of the First Partition of the Polish–Lithuanian Commonwealth.