Born as the son of a samurai in the Satsuma domain in southern Kyūshū in what is now Kagoshima Prefecture, Kuroki fought for the Shimazu clan against the Tokugawa shogunate forces in the Boshin War of the Meiji Restoration.

Promoted to the rank of general in November 1903, Kuroki was appointed commander of the Japanese First Army upon the outbreak of the Russo-Japanese War the following year.

[citation needed] In the 1915 Gallipoli Campaign he appointed Captain William Maxwell, a British journalist who had reported on the Russo-Japanese War for the London Daily Mail to be Chief Field Censor.

Despite his success and previous military record, Kuroki was one of two senior field commanders denied promotion to Field Marshal, thought to be largely because of his Satsuma origins at a time when the government was dominated by Chōshū rivals, although this may have been due to the internal politics within the Japanese Imperial Army of the time.

[6] Retiring from military service in 1909, he received the title of danshaku (baron) and later hakushaku (count) under the kazoku peerage system.