The village of Opatowiec was first mentioned in 1085, when Judyta, the wife of Prince Władysław I Herman, presented it to the Benedictine monks from Tyniec.

In 1271, Duke Boleslaw V the Chaste granted Opatowiec a town charter under Magdeburg rights, upon the request of abbot Modlibob.

The town became a local trade center, due to its location along the Vistula waterway, and on a merchant trail from Silesia in the west to Kievan Rus in the east.

In 1283, abbot Tomasz founded an abbey of the Dominican Order, and in 1341, King Casimir III the Great granted Opatowiec the right to organize trade fairs.

In the same year, King Casimir IV Jagiellon hosted at Opatowiec envoys from the Republic of Venice, to discuss war with the Ottoman Empire.