Up until the Second World War, Nowy Korczyn, by now a village, had a large Jewish community, many of whose members were murdered in the Holocaust.

In the Middle Ages, Nowy Korczyn was a trade village, located on a junction of busy merchant roads from Kraków to Kievan Rus', and from Kosice to Sandomierz.

In 1257, when the Duke stayed here with his wife Kinga of Poland, the pious couple decided to found a Franciscan abbey in Nowy Korczyn.

New, stone castle was built here in the 1350s by King Casimir III the Great, and it quickly emerged as one of the major royal residences in Poland.

In 1404, King Władysław Jagiełło called such a meeting, to discuss new taxes, needed for the planned purchase of the Dobrzyń Land from the Teutonic Knights.

On April 25 of the same year, powerful Cardinal Zbigniew Oleśnicki, who opposed Polish alliance with Czech Hussites, called a Confederation here.

In 1461, King Casimir IV Jagiellon hosted here envoys of George of Poděbrady, the Crimean Khanate, and the Margraviate of Brandenburg, and in 1465, szlachta of both Lesser and Greater Poland gathered here to discuss finances needed to end the Thirteen Years' War.

In 1470, Casimir IV Jagiellon met at the Nowy Korczyn castle with papal legate and envoy of Emperor Frederick III.

On 9 October 1479 Martin Truchseß von Wetzhausen, Grand Master of the Teutonic Knights, paid homage to the Polish king at Nowy Korczyn.

Here Lesser Poland sejmiks took place, in which regional senators and deputies of the Sejm met to discuss and coordinate their policies.

In 1549, King Sigismund II Augustus funded a hospital, and at that time, Korczyn was a major beer producer, with 19 small breweries.

Korczyn had a number of granaries, in 1566 a new town hall was built, and in 1568 a canal was completed, which connected the man-made lake Czartoria with the Nida river.