The T-28 was deployed during the Soviet invasion of Poland, and the Winter War against Finland. During the initial stages of the Winter War, the tank was used in direct fire missions against Finnish pillboxes. In the course of these operations, it was found that the armour was inadequate and an upgrade was initiated. The frontal armour plates were upgraded from 30 mm to 80 mm and side and rear plates to 40 mm thickness. With this up-armoured version, the Red Army broke through the main Finnish defensive fortification, the Mannerheim Line.
According to Russian historian Maksim Kolomiets in his book T-28. Stalin's Three-headed Monster, over 200 T-28s were knocked out during the Winter War, but only 20 of them were irrecoverable losses (including two captured by the Finnish Army). Due to the proximity of the Kirov Plant, all other knocked-out tanks were repaired, some of them over five times.
The Finns nicknamed the T-28 Postivaunu ("mail coach" or "postal train") after a lone Soviet T-28 tank commander was captured with his knocked out tank that carried the monthly salary of and mail addressed to the 91st Tank Battalion (this occurred 19–20 December 1939, during the battle of Summa). The T-28 was also nicknamed Kivitalo ("stone building") by the Finns due to its large size.
The Finns captured two T-28s during the Winter War and five in the Continuation War, for a total of 7 vehicles. The Finns did not have tractors that could tow away vehicles as heavy as the T-28, and so captured T-28s that could not move under their own power were stripped of anything useful (machine guns, radios etc.) and left where they were.
The Soviets had 411 T-28 tanks when the Germans invaded the Soviet Union in June 1941. A large majority of these were lost during the first two months of the invasion, many of them abandoned after mechanical breakdown. Some T-28s took part in the 1941 winter defence of Leningrad and Moscow, but after late 1941, they were rare in Red Army service; a few were operated by enemy forces.
Today, three T-28s remain, two in Finland and one in Moscow. One restored T-28 is on display in Finnish field camouflage in the Parola Tank Museum, Finland. A further wreck is stored at Parola, now awaiting restoration and a hull previously used as a bunker was discovered near St. Petersburg.