In 1941, backbone of the German Army's anti-tank units was the 3.7cm Pak 35/36, which had proved inadequate after encountering the French Char B1 bis and the British Matilda during the invasion of France. However, its successor, the 5cm Pak 38, was still in shortage. Fortunately, the German Army also had the 8.8cm FLAK 18/36/37 anti-aircraft gun that could also be adapted for anti-tank missions, which had temporarily compensated for their shortage of anti-tank weapons. Nevertheless, Pak 40 was still highly anticipated for the upcoming invasion on the eastern front.

Operation Barbarossa, the invasion of Russia, was launched in the summer of 1941. The German Army's encounter with the Russian KV-I and KV-II heavy tanks had revealed their weakness in anti-tank capability. Hence the Pak 40 was desperately pressed into battle in November 1941.

Powder chamber of the Pak 40 is greater in diameter than its barrel; powder would keep exploding when Projectile is already traveling through the barrel. This had made it a highly effective anti-tank, capable of penetrating armour of 12mm from a distance of 1 km.

From 1941 through 1945, the Pak 40/L46 saw action in every battlefield where the German army fought. Besides being mounted on the standard carriage, it was also mounted on various mobile chassis including armoured and half-track vehicles, even on aircrafts.