Pitt-Taylor was commissioned into the Army Militia as a second lieutenant in the 5th battalion of the Rifle Brigade (The Prince Consort's Own) on 4 December 1895. He transferred to the regular army as a second lieutenant in the 1st Battalion on 18 October 1899, as the Battalion was sent to South Africa to serve in the Second Boer War. They were part of the force sent to relieve Ladysmith, and as such he took part in the battles of Colenso (December 1899), Vaal Krantz and the Tugela Heights (February 1900). He was promoted to lieutenant on 1 August 1900, and served in Natal and in the Transvaal, staying in South Africa throughout the hostilities, which ended with the Peace of Vereeniging on 31 May 1902. For his service in the war, he was appointed a Companion of the Distinguished Service Order (DSO). Following the end of the war, Pitt-Taylor left Cape Town with other men of the battalion on the SS "Orissa", which arrived at Southampton in late October 1902, when the battalion was stationed at Portsmouth.