The regiment's enlisted soldiers were drawn from the native Africans, while most officers were seconded from the British Army.

Until independence, the parade uniform of the KAR comprised khaki drill, with tall fezzes and cummerbunds.

Prior to 1914, the regiment's field service uniforms consisted of a dark blue jersey and puttees, khaki shorts and a khaki fez cover with integral foldable cloth peak and neck flap, the designs according to Sealed Patterns procured from India.

In addition, they also wore brown leather equipment similar to the 1888 Slade–Wallace British equivalent, but locally produced.

Askaris wore sandals or were barefoot, on the rationale that the heavy military boots of the period were unsuitable for African recruits who had not previously worn footwear.

[2][3] Fezzes bore an Arabic or Roman number with the wartime-raised battalions wearing theirs on geometric-shaped patches of cloth.

[5] The 5th and 6th battalions were disbanded by 1910 as a cost-saving measure by the Colonial Office and out of white-settler concern over the existence of a large indigenous armed force.

During the early 1900s the King's African Rifles took part in the Somaliland campaign against Mohammed Abdullah Hassan (known to the British as the 'Mad Mullah') and the Dervishes.

Lt-Col. Alexander Cobbe of 1st (Central Africa) Battalion KAR, was awarded the Victoria Cross for his action at Erego, on 6 October 1902.

The increase in cadres was difficult due to the shortage of Swahili-speaking whites, as many white settlers had already formed segregated units such as the East African Mounted Rifles, the East African Regiment, the Uganda Volunteer Rifles and the Zanzibar Volunteer Defence Force.

In Armies in East Africa 1914–18, Peter Abbot notes that the KAR units recruited from former prisoners of war were used as garrison troops by the British, to avoid any conflict of loyalties.

[7] During the interwar period, the KAR was slowly demobilised to a peacetime establishment of six battalions, at which strength the regiment remained until the Second World War.

Under the terms of a war contingency plan, a brigade each was provided from the Gold Coast (now Ghana) and from Nigeria for service in Kenya.

In 1941, during the East African Campaign, Sergeant Nigel Gray Leakey of the 1/6th Battalion was awarded the Victoria Cross (VC).

[12] The 1st, 2nd, and 3rd battalions saw service in the Malayan Emergency, where they were heavily involved in fighting Communist rebels, suffering 23 dead.

It was gradually replaced by the newly formed Special Mobile Force (SMF) and Police Riot Unit (PRU).