Fourth Army or 4th Army may refer to:
Germany
- 4th Army (German Empire), a World War I field Army
- 4th Army (Wehrmacht), a World War II field army
- 4th Panzer Army
Russia - Soviet Union
- 4th Army (Russian Empire)
- 4th Army (RSFSR)
- 4th Army (Soviet Union)
- 4th Air Army, Soviet Union and Russia
- 4th Guards Army, Soviet Union
- 4th Tank Army, Soviet Union
Others
- 4th Army (Austria-Hungary)
- Fourth Army (Bulgaria)
- Fourth Army (National Revolutionary Army), Republic of China
- New Fourth Army, Republic of China
- Fourth Army (France)
- Fourth Army (Italy)
- Fourth Army (Japan)
- Fourth Army (Ottoman Empire)
- Fourth Army (Romania)
- Fourth Army (United Kingdom)
- Fourth United States Army
- 4th Army (Kingdom of Yugoslavia)
See also
- IV Corps (disambiguation)
- 4th Division (disambiguation)
- 4th Brigade (disambiguation)
- 4th Regiment (disambiguation)
- 4th Squadron (disambiguation)