The oldest written mention of Inowrocław dates back to 1185. At the time, it was already a large market settlement called Nowy Włodzisław and belonged to the Masovian Dukes. According to tradition, it had been established by settlers from Włocławek.
Around the year 1231, Inowrocław became the capital of the Duchy of Kuyavia. The duke chartered it under the Magdeburg law ca. 1238. In 1267, it became the capital of the independent Duchy of Kuyavia.
At the turn of 1321, a trial between Poland and the Teutonic Knights was held before the papal court in Inowrocław, as a result of which the Order was ordained to cede ownership of Pomerania. In 1327, the duchy was incorporated into the Kingdom of Poland. In the years 1332–1343, the town was conquered by the Teutonic Knights, and later it became a Polish fief. In 1377, negotiations were held between King Casimir the Great and Grand Master of the Teutonic Order Dietrich von Altenburg. The same year, Louis the Hungarian granted Inowrocław as a fief to Duke Władysław Opolczyk (until 1396). A great political convention was held in the town in 1397, with Queen Jadwiga meeting with Master Konrad von Jungingen. The year 1431 saw the town pillaged by the Teutonic Order.
King Casimir Jagiellon renewed the town charter in 1450 and granted new privileges to the townspeople. Inowrocław continued to serve as an important centre of trade and crafts. One of the most vibrant branches of the local economy was the cloth industry. There were also several guilds operating in the town, among them the associations of shoemakers, tailors, furriers, and brewers. The town was surrounded by walls with three gates and 16 towers. Within the walls, there was the ducal castle, two churches, a monastery, a mint, and the town hall.
Inowrocław became largely depopulated during the plague in 1624. It was also completely devastated by the Swedes, who entered the town in 1656. It never managed to regain its former glory. In 1666, during the Lubomirski Rebellion, a battle between the mutineers and the royal army took place near Mątwy, not far from Inowrocław.
In the years 1772–1919, when it formed part of the Prussian Partition, Inowrocław was an important centre of Polish culture and the struggle for independence. The development of the town was boosted by the discovery of local rock salt deposits in 1835; they were considered some of the richest in entire Europe. A mine and a salt production plant started to operate in the area in 1873. In 1876, a balneological spa was opened in Inowrocław. In 1872, the town gained a railway connection with Bydgoszcz and Poznań, and in 1873 with Toruń. In 1882, a soda factory was opened in Mątwy (today – a district of Inowrocław). A tram network was established in the town in 1912.
In 1919, Inowrocław became part of independent Poland. During the German occupation in the years 1939–1945, the town was incorporated directly into the Third Reich. Germans carried out a mass-scale campaign of displacement directed against the local Polish and Jewish population. On the night of 30 November 1939, over 1,000 Polish families were banished from the town. A transit camp operated in Inowrocław in the years 1940–1945, with a total of ca. 10,000 prisoners held in the facility throughout its existence. A POW camp was established in the district of Mątwy. Several hundred people were murdered in each of the camps.
Since 1999, Inowrocław has been the capital of the Kujawsko-Pomorskie Province.
- Dzieje Inowrocławia, vol. 1–2, ed. M. Biskup, Warsaw – Poznań – Toruń 1978.