Casimir I of Kuyavia | |
|---|---|
 | |
| Born | c. 1211 |
| Died | 14 December 1267 |
| Buried | Cathedral of Włocławek |
| Noble family | House of Piast |
| Spouse(s) | Jadwiga Constance of Wrocław Euphrosyne of Opole |
| Issue | Leszek II the Black Ziemomysł Władysław I the Elbow-high Casimir II Siemowit Euphemia |
| Father | Konrad I of Masovia |
| Mother | Agafia of Rus |
Casimir I of Kuyavia (Polish: Kazimierz I kujawski; c. 1211[1] – 14 December 1267) was a Polish prince and a member of the House of Piast. He was Duke of Kujawy after 1233, ruler over Ląd from 1239-1261, ruler over Wyszogród after 1242, Duke of Sieradz from 1247-1261, Duke of Łęczyca after 1247, and Duke of Dobrzyń after 1248.
He was the second son of Konrad I of Masovia and his wife Agafia of Rus. He was probably named after his grandfather, Casimir II the Just.