| Native Name: | |
| Conventional Long Name: | Duchy of Livonia |
| Common Name: | Livonia |
| Era: | Early Modern Age |
| Religion: | Roman Catholic |
| Subdivision: | Vassal |
| Nation: | Lithuania |
| Status Text: | Vassal of Grand Duchy of Lithuania, then of the Polish–Lithuanian Commonwealth |
| Government Type: | Principality |
| Year Start: | 1561 |
| Year End: | 1629 |
| Event Start: | Treaty of Vilnius |
| Date Start: | 28 November |
| Event1: | Polish–Swedish War |
| Date Event1: | 1620–1622 |
| Event End: | Truce of Altmark |
| Date End: | 25 September |
| P1: | Terra Mariana |
| P2: | Free City of Riga |
| S1: | Swedish Livonia |
| S2: | Inflanty Voivodeship |
| Image Map Caption: | Polish–Lithuanian Commonwealth with its major subdivisions after the 1618 Truce of Deulino, superimposed on present-day national borders. Livonia here is coloured dark grey, upper-right, over modern Estonia and Latvia. Swedish Estonia is coloured green.[1] |
| Capital: | Fellin (Viljandi) |
| Leader1: | Sigismund II Augustus |
| Year Leader1: | 1561–1572 |
| Leader2: | Henry III de Valois |
| Year Leader2: | 1573–1575 |
| Leader3: | Stephen Báthory and Anna Jagiellon |
| Year Leader3: | 1576–1586 |
| Leader4: | Sigismund III Vasa |
| Year Leader4: | 1588–1621 |
| Title Leader: | Grand Duke of Lithuania and King of Poland |
| Deputy1: | Jan Hieronimowicz Chodkiewicz |
| Year Deputy1: | 1566–1578 |
| Title Deputy: | Governor |
The Duchy of Livonia,[2] also referred to as Polish Livonia or Livonia, was a territory of the Grand Duchy of Lithuania and later the Polish–Lithuanian Commonwealth that existed from 1561 to 1621. It corresponds to the present-day areas of northern Latvia and southern Estonia.
Livonia had been part of the Grand Duchy of Lithuania from 1561, since the Livonian Order was secularized by the Union of Vilnius and the Livonian Confederation dissolved during the Livonian Wars. Part of Livonia formed the Duchy of Courland and Semigallia while the south-west part of today's Estonia and north-east part of today's Latvia, covering what are now Vidzeme and Latgale, were ceded to the Grand Duchy of Lithuania.
In 1566, it was declared the Duchy of Livonia according to the Treaty of Union between the landowners of Livonia and authorities of Lithuania; Jan Hieronimowicz Chodkiewicz became the first Governor of the Duchy (1566–1578) in Sigulda Castle. It was a province of Grand Duchy of Lithuania until 1569. After the Union of Lublin in 1569, it became a joint domain of the Polish Crown and the Grand Duchy.
The larger part of the Duchy was conquered by Swedish Empire during the Polish–Swedish wars, and their gains were recognized in the Truce of Altmark in 1629. The Commonwealth retained southeastern parts of the Wenden Voivodeship, renamed to Inflanty Voivodeship with the capital in Daugavpils (Dyneburg), until the first Partition of Poland in 1772, when it was annexed by Catherine the Great's Russian Empire. The title "Prince of Livonia" was added to the grand title of later Russian Emperors.