On 25th November 1901 it was announced that the Imperial Government had accepted the offer, made by Canada, of a force of 600 mounted men. Recruiting at once commenced, and on 14th January 1902 470 men sailed on the Manhattan, the remainder embarking on the Victorian about the 28th, making a contingent of six squadrons. A field hospital accompanied the contingent. The total strength sent was nearly 900. On arrival in South Africa the regiment, which was commanded by Colonel Evans, was taken to the Western Transvaal, where Lord Methuen had met with serious reverses shortly before, and they were employed under Major General Walter Kitchener and Lieutenant General Ian Hamilton. On 31st March 1902 Major General Kitchener had sent forward two columns, those of Colonel Keir and Colonel Cookson, with the latter of whom were the newly arrived Canadian MR, Damant's Horse, and two squadrons of Yeomanry. At Brakspruit Colonel Cookson, after being engaged with the enemy, decided to halt, entrench, and close up his baggage. In his despatch of 8th April 1902 Lord Kitchener said: "At 1.20 pm the enemy opened fire with three guns and a pom-pom, and then under cover of their artillery attempted to rush the eastern side of the camp". After very heavy fighting the enemy withdrew. Lord Kitchener adds: "The heaviest loss in this engagement fell upon the Canadian Mounted Rifles, who, in this, their first fight of importance since landing, displayed the utmost bravery and determination. Lieutenant Bruce Carruthers of the regiment especially distinguished himself. Being in command of a detachment of the rear-guard, when coming into camp he remained out in a position of observation, in which he eventually found himself isolated and surrounded by a large body of the enemy. Rejecting all idea of surrender, however, his small patrol of 21 men fought stubbornly on to the end, no less than six of their number, including Lieutenant Carruthers, being killed and 12 wounded. There have been few finer instances of heroism in the whole course of the campaign. The Boers who took part in this unsuccessful attack upon Colonel Cookson's camp were estimated to have numbered 1800 men, and were under the command of Generals Delarey and Kemp". In this action, generally referred to in the despatches and elsewhere as that of Boschbult, the Canadians lost Lieutenant Carruthers and 11 men killed, and Captain F S M Howard and Lieutenants R H Ryan, G B Mackay, R F Markham, and A T London, and 42 men wounded. Major wired to the Minister of Militia of Canada: "regiment and field hospital have undergone sev. test, and have acquitted themselves most creditably. I regret the heavy losses". Lord Roberts telegraphed his congratulations to the Governor-General as well as to South Africa.
The regiment took part in the last great drive between the Klerksdorp blockhouse line and the railway running from Kimberley and Vryburg to Mafeking. In these drives many prisoners were taken.