Mikołaja Cudotwórcy; Russian: Николаевский собор) is an historic Orthodox cathedral in Bialystok, Poland St. Nicholas is the cathedral of the Bialystok-Gdańsk diocese of the Polish Autocephalous Orthodox Church and the seat of the Bialystok parish of St. Mikołaj (in the deanery of Białystok).

Such a hypothesis, presented by Przemysław Czyżewski, is evidenced by the inscription on the church antimine, which was signed by bishop Leon Załęski in 1708.

In 1773 the building was described as follows: "wooden, plastered with lime, roofed tiles, with three domes, with iron crosses, gold-plated knobs".

A new St. Nicholas church was built due to the rising population of Białystok as a result of the development of local industry.

In October 1838, the design of the St. Nicholas church was entrusted to the architect, Mikhailov, but there is no clear evidence that he is the author of the building plan.

The cemetery, which originally surrounded St. Nicholas, and the preserved tombstones were moved to the hill with the chapel of St. Mary Magdalene.

[5] St. Nicholas became the seat of the Orthodox parish, taking over the functions of the chapel of St. Alexander Nevsky in the Branicki Palace.

The new St. Nicholas church was built in the classical style, with elements referring to the architecture of antique, as well as to Byzantine cross-dome temples.

According to the equipment list from 1859, five bells were located on its belfry, while the Bialystok Icon of the Mother of God was the object of worship of both the Orthodox and Catholic people.

That same year, a group of Russian painters, under the leadership of Mikhail Avivov, created a new decoration, modeled in their work on the frescoes of Viktor Vasnetsov from the Cathedral of St. Włodzimierz in Kiev.

After the restoration of Polish independence in 1918, the new government viewed the Orthodox religious buildings in Bialystok as symbols of the previous Russification policy and revised them for the Catholic Church.

On September 7, 1951, the Council of Bishops of the Polish Autocephalous Orthodox Church founded the diocese of Białystok-Gdańsk and designated St. Nicholas as its cathedral.

In the first years after World War II, the Polish Ministry of Public Security conducted surveillance of the clergy serving at St. Nicholas as part of the object case codenamed Mikołaj.

The exterior plasters of the building were replaced, the kiots and the iconostasis were renovated and gilded, and the roof and domes were covered with copper sheet.

The procession from the city limits to St. Nicholas was observed by over 70,000 spectators, including nine Orthodox bishops, from the Polish Autocephalous Orthodox Church and the Belarusian Exarchate, as well as the Roman Catholic Archbishop of Bialystok Edward Kisiel and the Voivode of Białystok Voivodeship, Stanisław Prutis.