The iconostasis, 12 meters high, includes contributions from Russian tsars, such as the icon "John the Baptist – Angel of the Desert" (mid-16th century) donated by Ivan the Terrible; "Vladimir Mother of God" (late 16th century) from Tsar Feodor Ivanovich and Irina Godunova; "Holy Princes Boris and Gleb" (late 16th century) from Boris Godunov; "Christ Pantocrator" (1683) by Simon Ushakov; and "Selected Saints" (1666) by Fyodor Zubov, eminent 17th-century icon painters. The highlight of the iconostasis is its intricately carved gilded wooden frame, consisting of 84 columns carved in high-relief openwork from single linden trunks by Kremlin Armory masters Osip Andreyev and Klim Mikhailov. Gilding was completed by the renowned craftsman Dorofey Zolotaryov.
The preserved wall paintings from the 16th–17th centuries cover the entire surface of the walls in the Smolensk Cathedral. The main theme of the paintings is the Akathist—a hymn of praise to the Mother of God. The glorification of Mary is depicted in 24 illustrations dedicated to the Akathist. Another significant theme is the unification of Russian principalities around Moscow, the creation and strengthening of the Russian state. This theme is reflected in the paintings on the columns, which depict saints and Russian princes representing lands incorporated into the Russian State by the late 15th and early 16th centuries.
The main chamber of the Smolensk Cathedral houses the burial sites of royal women: the white-stone tombs of Tsarevna Sophia Alekseyevna (1704), her sisters Yevdokiya Alekseyevna (1712) and Catherine Alekseyevna (1718), and Peter I’s first wife, Yevdokiya Fedorovna Lopukhina (1731). Beneath the altar in the undercroft lie the tombs of other royal family members, including Tsarevna Anna, the eldest daughter of Ivan the Terrible, who lived about a year; Princess Ulyana Paletskaya, widow of Ivan’s younger brother Yuri; and Tsarevna Elena Sheremeteva, widow of Ivan Ivanovich, the eldest son and heir of Ivan the Terrible who was killed by his father. Other parts of the undercroft house the burials of boyar and princely families, such as the Zakharin-Yurievs, Vorotynskys, Kubenskys, and Khitrovo.
Currently, restoration work is underway in the Smolensk Cathedral in preparation for the 2024 celebrations marking the 500th anniversary of the Novodevichy Convent.