The miracle working Icon of Mother of God of Kozelštšan is definitely the most famous Icon at the cathedral. It was situated in Viborg where it became known for the miracles it performed. It was gifted to a merchant family by John Khronstad ,who was later canonized,and it healed the deadly ill daughter of the family. It was moved to the Uspenski Cathedral following the 2nd world war where Russia usurped Viborg from Finland.

It was stolen from the cathedral in 2010, though it was found half a year later at a park in Turku. The thieves were caught, and they confessed that the icon was hidden underground. Most of the original gold and pearl cover was lost and all of the rings and jewelry that had been gifted to the icon were also lost forever. The painting had also suffered some damage and was restored in the Valamo Monastery, and it was returned to the cathedral in 2011. 

The icon is surrounded by jewelry. These are offerings to the icon from people who feel like their prayers have been answered and people still bring rings and jewelry to the point where the canvas has gotten too heavy to support all of them.