The cathedral, dedicated to the icon of the "Mother of God of Smolensk," is one of the first memorial churches in the Volga region, built in honor of Emperor Alexander II during his lifetime. The construction of this majestic structure in the small town of Kozmodemyansk was initiated after the miraculous salvation of the emperor from an assassination attempt on April 4, 1866. The initiators of the construction were retired provincial secretary M. I. Diakonov, merchants Yakov Morozov and Vasily Zamyatin, as well as residents of the town who were concerned about the incident. The cathedral's design was commissioned from the architect Konstantin Ton, who worked in the popular Russian-Byzantine style of that time.

The Kozmodemyansk cathedral, built and consecrated by 1872, externally resembles the Moscow Cathedral of Christ the Savior: its walls are topped with keel-shaped medallions, the facade is adorned with faceted columns and domes. The keel-shaped arches that complete the cube of the cathedral are repeated in the window designs, with their white paint contrasting effectively against the red-brown background of the walls. All this gives the facade a monumental and festive appearance. The ribbon of the cornice visually separates the upper parts of the building from the main structure. The wide domes with crosses simultaneously evoke the image of a royal headdress and the helmets of Russian warriors.

The five-domed structure was later supplemented with seven bells, the largest of which weighed 139 poods and 10 pounds, and its sound could be heard for many kilometers. The cathedral has three altars: the main one is dedicated to the Smolensk Icon of the Mother of God, the right one to Archangel Michael, and the left one to Prince Alexander Nevsky. Inside the church, four powerful columns support the vault, with the choir located on the northern side. The walls and upper vaults were decorated with oil paintings. The main relics of the church were ancient icons, such as the Ascension of the Lord, St. Archangel Michael, and the Smolensk Mother of God. Two chapels were attached to the church: one in honor of the 300th anniversary of Kozmodemyansk, and the other in honor of the ascension of Alexander III to the throne. A church-parish school was opened at the cathedral.

Unlike other churches in Kozmodemyansk, which were destroyed during religious persecutions, the Smolensk Cathedral suffered less. Although church services ceased in the late 1920s, the establishment of local history and art museums within it saved the building from demolition. In 1929, the cathedral lost its five domes, and the bell tower was dismantled. The former church premises were urgently prepared for museum exhibitions. During the renovation and dismantling of the iconostasis and other cult items, magnificent frescoes were hidden under lime wash. In 1975, at the request of museum workers, a cosmetic repair was carried out, resulting in some of the frescoes being partially cleaned. At that time, the restorer Efimov Izmail Varsanofyevich worked here, restoring small fragments of frescoes depicting angels and the disciples of Jesus Christ.

Only in the late 1990s did the Smolensk Cathedral once again become the spiritual center of Kozmodemyansk. In a short time, the five domes were restored, and the recreation of the interior decoration began. The first services were held in 1998, even before the restoration work was completed. The interior of the cathedral was adorned with a gilded carved iconostasis, arched vaults and columns covered with intricate painting, as well as a heavy gilded chandelier, serving as part of the lighting system and a decorative element. In 2008 and 2012, the restoration of 19th-century oil paintings was carried out by St. Petersburg restorers Yuri Goshparenko and Anton Klyushanov. In 2004, the construction of a new bell tower was completed, for which new bells were cast with the help of benefactors. Today, the Smolensk Cathedral is the main architectural landmark of the Mari El Republic and a symbol of the spiritual renewal of Kozmodemyansk.