The Cathedral of St. Nicholas the Wonderworker in Omsk is often referred to as the Nikolsky Military Cossack Cathedral, as it was originally built for the Cossack army. The idea for the construction of the church arose from the command, and the funds for its erection were collected through donations. The church project was developed by architect P. Stasov, known for his works in Moscow and St. Petersburg. After all necessary changes were made, the project was approved. Construction of the cathedral began in May 1833 on a square that also housed the Cossack cadet corps, and the consecration took place in June 1840. The icons for the church were created by artists M.I. Myagkov and P.M. Skorospelov.

The central part of the church was topped with a lowered dome, above which rose a decorative semicircular dome. Nearby was a refectory with a domed vault and a bell tower. Among the parishioners were both Omsk Cossacks and peasants from nearby villages. The cathedral housed the banner of Ermak, which disappeared after 1919.

In November 1928, the authorities decided to use the cathedral building for city needs, including cultural ones. The bell tower was dismantled, and the bells were melted down. Subsequently, clubs, a music school, the cinema "Victory," and other institutions were located here. In 1960, the cathedral was threatened with demolition, but protests from the townspeople helped preserve it. Restoration took place in the 1970s and 80s. Later, an organ was installed in the church, and organ and chamber music could be heard here.

In 1989, the cathedral was handed over to the Omsk diocese, and since June 1998, it has been under the management of the Omsk-Tara diocese. On August 8, 2004, in honor of the 288th anniversary of Omsk, the banner of Ermak was taken out of the cathedral, symbolizing respect for the memory of ancestors who fought for Holy Russia and the Orthodox faith.

Today, the interior decoration of the church has changed significantly: a new iconostasis was created according to the design of Vasily Gulchenko, and its gilding was done by Oleg Zotin. The icons were painted in the diocesan workshop under the guidance of Gennady Adaev and icon painters Dmitry Fofin, Tatyana Golubeva, Arthur Kostylyov, Vladimir Khodykin, Dionysius, and Natalia Nepobedimy. The cathedral actively lives a spiritual life, with Divine Liturgies, baptisms, weddings, and other rites held daily.