The church was put up opposite to the town, on a hill on the left bank of the Slupia River. The first document on the church appeared in 1269 and actually talked about church chaplain Herman mentioned in a document issued by Gdansk Pomerania duke Msciwoj II and addressed to the Cistercian order in Bukowo. Herman's name was known by historians already in 1240 when he was given the Ryczewo village from Swietopelek II. Now, this village is one of Slupsk districts. We should also mention about a privilege from 1276 when duke Msciwoj II gave a mill next to St Nicolaus' Church to the village administrator of the German commune. The church was a wooden sanctuary as such constructions predominated at that time in Pomerania. Almost without doubt, it was built by duke Swietopelek II as he ruled the Slupsk area in that period. The church itself held a status of a private church.

The church incomes varied from ones of St Peter's Church and Blessed Virgin Mary's town chapel built before, located on the right bank , that collected tithes from certain villages. St Nicolaus' Church got a part of incomes from nearby fields, mills, meadows and pastures. A type of its endowment and a name of its patron tell us that the sanctuary was located in an area with an intensive activity of merchants and craftsmen. To the south of the church hill, there was the first village of German settlers who came to Slupsk from Lübeck. Following duke's permission, the settlers established a municipality here. Their administrator was Henryk de Werciberg we talked about earlier. On the right, opposite bank of the Slupia River, a Kashubian village with parish St Peter's Church was situated. The first drawing of St Nicolaus' Church that can give us an image of the building came from Lubinus' map. We can find it in the northern part of the town, together with the Premonstratensian convent that were right next to the church. We should take a look at another (different than the today's one) tower shape that ended with a conical spire.

Since St Nicolaus' Church was a private church of Gdansk duke Swietopelek II, Slupsk residents began to build their own sanctuary – St Maurice's Church. According to research carried out by Slupsk historian Barbara Popielas-Szultka, St Maurice was a originator of Blessed Virgin Mary's Church. While knights of the Teutonic order ruled Slupsk between 1329 and 1332, a name of the patron was changed to a one following a Marian tradition of the order. In 1281, the urban commune returned St Nicolaus' Church to a successor of Swietopelek II – duke Msciwoj II. In the same year, Msciwoj passed the villages in the Slupsk area together with St Nicolaus' Church to the Premonstratensian order from Bialoboki on the River Rega. Donations from duke Msciwoj II were supposed to give money necessary to build a Premonstratensian convent in Slupsk. Nuns came to Slupsk in 1284, their order was a branch of the male Premonstratensian order from Trzebiatow. A main goal of the order was a pastoral work.

The oldest location of the convent was right beside St Nicolaus' Church. We do not know now how the building looked in the past but we can suppose that it was made from wood and covered with straw, in the same way as the sanctuary was. In 1311, the order got Brandenburg margraves' approval to put up new masonry buildings in the town. After a thorough study on a certain fragment of medieval defence walls of Slupsk, we know now that the masonry church was built at the end of the 14th century or at the beginning of the 15th century. The convent buildings were being built along with the church. The eastern top wall of the church faced the Slupia River and the western front side was directed towards today's Grodzka Street (Holstentorstrasse). The convent separated from the church walls with a narrow street – called Kreta Street now (Holtentormauerstrasse) – was situated to the north of the church. Both the convent and the church itself had basements and were built on stone foundations. The convent was one floor high. Nowadays, they suppose that the church tower was built onto the main construction after a fire in 1477 as earlier, according to the Premonstratensian order's rule, the church had only a small tower with a small bell inside. The fire burnt down the organ and other elements of the interior. In 1665, a huge fire in the town destroyed the church and the convent again. In 1679, restoration of the convent was completed. On the other hand, the church was only covered with a roof due to lack of money for further works. The church was rebuilt in 1737 with efforts of Col. Steding and it was then consecrated to become a garrison church.

However, when the colonel went to fight in the Silesian War in 1740, results of his earlier endeavour were left behind and the Protestant church was turned into a storeroom and a space for keeping carriages and other vehicles. In 1760, following an approval of the city council, the Russian Army (the 7 Years' War) staying in Slupsk used St Nicolaus' Church as an Orthodox church. Later, it was used as a storeroom and a fire station, slowly falling into ruin. About 1770, the city council decided to use the building for educational purposes and, in 1772, it became a boarding school for the poorest children. During an overhaul, the damaged cupola located between four pinnacles was removed.

Another modifications to the construction of the former church were made in 1819 and they were supposed to make the building meet conditions necessary for establishing a primary school. In 1834, the first female high school in Slupsk was brought to life. Since 1926, St Nicolaus' Church was a place where a school for backward children was located (Hilfsschule). The former Premonstratensian convent turned into a foundation of ladies from the Froulenstift family. Despite the fact that the order underwent many changes, it was kept in the same place for over 600 years. In March 1945, during a fire set by the Red Army in the Old Town, St Nicolaus' Church burnt down. The nearby convent, devastated and abandoned, was finally pulled down in order to get bricks back. In 1961, the Poznan Historic Object Conservation Workshop drew up historical documentation in order to completely rebuild St Nicolaus' Church and adapt it for use of a municipal library. On 10th September 1971, a formal opening of the library took place. It was named after Maria Dabrowska.