Mechanized infantry are infantry troops that use armoured fighting vehicles for transport and as heavy weapons support in combat. This kind of infantry is a development of the common infantry, and the tactics are usually more aggressive.

Mechanized infantry in its current form was first developed during World War II, where German panzergrenadier troops used an early variant. Half-track armoured personnel carriers and assault guns were permanently assigned to infantry units which developed into specialized mobile warfare offensive units such as the Großdeutschland Division and Waffen SS Panzer Grenadier.

The post-war Soviet Red Army and NATO further developed the doctrine and mechanized infantry was rapidly integrated into both armies.