| Native Name: | Księstwo inowrocławskie (pl) |
| Conventional Long Name: | Duchy of Inowrocław |
| Common Name: | Inowrocław |
| Era: | High Middle Ages |
| Status: | Province of Poland Fiefdom of the Polish Crown (from 1300) |
| Year Start: | 1267 |
| Year End: | 1364 |
| Event Start: | Split of Duchy of Kujavia after Casimir I's death |
| Event1: | Vassalized by Kingdom of Poland |
| Date Event1: | 1300 |
| Event2: | Occupation by Teutonic Order |
| Date Event2: | 1332–1337 |
| Event End: | Incorporated by the Polish Crown |
| P1: | Duchy of Kuyavia |
| Border P1: | no |
| S1: | Inowrocław Voivodeship |
| Flag S1: | POL województwo brzeskokujawskie IRP COA alt.svg |
| Border S1: | no |
| S2: | Duchy of Gniewkowo |
| Government Type: | Duchy |
| Religion: | Roman Catholic |
| Image Map Caption: | Duchy of Inowrocław within Kingdom of Poland between 1275 and 1300. |
| Capital: | Inowrocław |
| Today: | Poland |
The Duchy of Inowrocław (Polish: Księstwo Inowrocławskie) was one of the territories created during the period of the fragmentation of Poland. It was originally part of the Duchy of Kuyavia, but was separated by Ziemomysł and Władysław I the Elbow-high, upon the death of Duke Casimir I in 1267.
The Inowrocław Voivodeship was established on the territory of duchy in 1364.