The KV-122 was a proposed Soviet upgrade to the KV-85, designed with the intent of being able to compete with the firepower and armour of German heavy tanks near the end of World War II. The idea was to equip the existing KV-85s with copies of the turret and gun of the IS-2. By doing so, the tank would be able to engage German heavy tanks with high effectiveness despite their thick armour. However, the KV-122 project never progressed beyond a single prototype due to a combination of various factors. Firstly, the Soviet Union had already shifted its focus towards more capable tanks like the IS-2. Secondly, it was deemed unnecessary to recover the relatively small number of KV-85s on the frontlines, upgrade them, and then re-deploy them into combat. And finally, the Soviet Union faced too many logistical challenges to support the production and deployment of the KV-122 tanks. These challenges included limited resources (caused by a lot of KV-85s being lost), difficulties in transporting the heavy tanks, and a shortage of skilled personnel to operate and maintain them, as those were focused on more advanced tanks.

The KV-122 was introduced in Update 1.63 "Desert Hunters". The turret and gun, which are copies of those found on IS-2, are two of its most obvious differences that set it apart from previous models. A less noticeable difference is the engine, which was replaced with a V-2IS capable of producing 520 hp as opposed to the V-2K found on most KV variants, which is capable of producing 600 hp. Overall, it plays like an IS-2 with the convenience of a lower battle rating.