Kuyavia (sometimes spelt Cuyavia, Polish Kujawy) is a historical region of Poland, between the Vistula to the east and Noteć river to the west and between Noteć and Krówka river to the south.

Initially, in early Middle Ages the region was limited mostly to the Land of Kruszwica and politically it was a part of Greater Poland. With time, in 12th century the political influence of local dukes was extended to large parts of Masovia. Because of fertile lands and plentiful rivers the region was developing rapidly and the population also grew.

The political history of Kuyavia is as complicated as the one of nearby Masovia. In 11th century there was a bishopry established in Kruszwica. It was soon abolished, but was reintroduced in 1123 or 1124 and the capital of the region was moved to Włocławek.

In 1186 the area was conquered by Mieszko III the Old, who established there a duchy for one of his sons, Bolesław. After the latter's death in 1195 it was again incorporated to Masovia. Around 1231 Duke Konrad I of Masovia re-established the duchy as a property of his son Kazimierz I of Masovia. After his death in 1267 the duchy was further divided onto two separate lands ruled by his successors, with capitals in Inowrocław and Brześć Kujawski.

Initially a part of the Masovian domain, between 1248 and 1352 it was also attached to the Land of Dobrzyń, which was lost to the Teutonic Order. In 1287 Kuyavia became a separate duchy of its own domain. In 1332 the area of Kuyavia was conquered by the Teutons who controlled it until 1343. However, their control over these lands was found unlawful by the papal court and until 1364 the area was gradually reconquered by Poland.

As part of Poland, the area retained its traditional division onto two separate parts, that was sanctioned by the administrative division onto Inowrocław Voivodship and Brześć Kujawski Voivodship, that shared the same Sejmik in Radziejów. Following the first partition of Poland in 1772, the northern part of Kuyavia was annexed by Prussia. The annexation of the rest of the region followed in 1793, after which it was directly incorporated into a Prussian province of "New East Prussia".

Between 1807 and 1815 the area was a part of the Duchy of Warsaw, but after the fall of Napoleon Bonaparte it got again under foreign domination. Most of the area with the biggest cities of Bydgoszcz, Inowrocław and Kruszwica was again annexed by Prussia, while the easternmost part with Radziejów and Włocławek was annexed by Russia and passed to the Kingdom of Poland. Since 1918 the area is yet again a part of Poland. Since 1999 most of the area belongs to the Kuyavian-Pomeranian Voivodship.