The Army of the West was the name of the United States force commanded by Stephen W. Kearny during the Mexican–American War, which played a prominent role in the conquest of New Mexico and California.

Colonel Stephen W. Kearny initially commanded some 1,700 regular army and volunteer soldiers mustering at Fort Leavenworth, Kansas.

Kearny was promoted to brigadier general, and he designated the force the Army of the West and advanced on the Santa Fe trail by the end of June 1846.

Once in San Diego, Kearny's force was augmented with reinforcements of marines and naval infantry under Commodore Robert F. Stockton's command.

With a combined force now numbering 500, Kearny and Stockton moved north to attack Pico's Californians near Los Angeles.

The last major action of the army came in 1848 when Price, recently promoted to the rank of general, invaded the state of Chihuahua and defeated a Mexican force at the Battle of Santa Cruz de Rosales.