The Sturmtiger was intended to serve as a heavy infantry support vehicle, rendering assistance with attacks on heavily fortified or built-up areas. By the time the first Sturmtigers were available, however, the situation for Germany had changed for the worse, with the Wehrmacht being almost exclusively on the defensive rather than the offensive.
Three new Panzer companies were raised to operate the Sturmtiger: Panzer Sturmmörser Kompanien (PzStuMrKp) ("Armored Assault Mortar Company") 1000, 1001 and 1002. These originally were supposed to be equipped with fourteen vehicles, but this figure was later reduced to four each, divided into two platoons.
PzStuMrKp 1000 was raised on 13 August 1944 and fought during the Warsaw Uprising with two vehicles, as did the prototype in a separate action, which may have been the only time the Sturmtiger was used in its intended role. PzStuMrKp 1001 (commanded by Captain von Gottberg) and 1002 (commanded by Lieutenant Zippel) followed in September and October. Both PzStuMrKp 1000 and 1001 served during the Ardennes Offensive, with a total of seven Sturmtigers.
After this offensive, the Sturmtigers were used in the defence of Germany, mainly on the Western Front.
During the battle for the bridge at Remagen, German forces mobilized Sturmmörserkompanie 1000 and 1001 (a total of 7 units), and attached them to the 6th SS-Panzer Armee to take part in the battle. The Sturmtigers were originally tasked with using their howitzers against the bridge itself, though it was discovered that they lacked the accuracy needed to effectively hit the bridge. During this engagement, some reports suggest that one round from one of the howitzers managed to land between or nearby a group of Sherman tanks, obliterating them. However, given the inaccuracy of the Sturmtiger's gun, as well as the involvement of dive bombers, and a railway gun in the battle; this story has never been confirmed. After the fall of the bridge to the Allies, Sturmmörserkompanie 1000 and 1001 were tasked with bombardment of allied forces to cover the German retreat, as opposed to the bunker busting for which they were originally designed.