Takeo Itō was born in the city of Fukuoka in the Fukuoka prefecture[1] The commanding officer of the IJA 228th Infantry Regiment at the start of the Second Sino-Japanese War, he assumed command of 114th Infantry Regiment in August 1940.

[3] In early 1942, Itō was reassigned to an independent command in his own name, the "Itō Detachment", consisted mainly of 228th Infantry Regiment, 38th Infantry Division and the 1st Kure SNLF, which took part in the Battle of Ambon[4] in the Dutch East Indies (30 January–3 February 1942), and in the occupation of Timor.

On 11 November, during the pivotal Battle of Guadalcanal, Itō was positioned by Lieutenant-General Harukichi Hyakutake to attack Marines under the command of United States General Alexander Archer Vandegrift who were involved in the Matanikau offensive against Japanese positions.

However, Vandegrift called off his offensive that day after receiving intelligence reports of Hyakutake's plans.

Itō became commander of the 40th Independent Mixed Brigade, stationed at New Ireland on 8 July 1944.