The office of the Prime Minister was created by the Responsible Government Act of 1872 and Sir John Charles Molteno became the first Prime Minister of the Cape (1872 – 1878). Initially the Prime Minister’s department fell under the Ministerial Division of the Colonial Secretary. However, in 1889 a separate ministry was established. In 1891, this office was again placed under the Colonial Secretary but separated later in 1894.

The function of the Prime Minister’s office was to act as a medium of communication between the Governor and the Government. It dealt with despatches between the Colonial and Imperial governments and with correspondence between other British Colonies and dependencies. Communications between the two legislative branches and the government passed through the Prime Minister’s Office, from which emanated all instructions affecting the public service as a whole. In December 1908 the Ministerial Division of the Prime Minister was abolished and the office once again came under the administration of the Colonial Secretary until 1910.

Prime Ministers, 1872 – 1910:
Sir John Charles Molteno, 1 December 1872 – 5 February 1878
Sir John Gordon Sprigg, 6 February 1878 – 8 May 1881
Thomas Charles Scanlen, 9 May 1881 – 12 May 1884
Sir Thomas Upington, 13 May 1884 – 24 November 1886
Sir John Gordon Sprigg, 25 November 1886 – 16 July 1890
Cecil John Rhodes, 17 July 1890 – 12 January 1896
Sir John Gordon Sprigg, 13 January 1896 – 13 October 1898
William Philip Schreiner, 13 October 1898 – 17 June 1900
Sir John Gordon Sprigg, 18 June 1900 – 21 February 1904
Sir Leander Starr Jameson, 22 February 1904 – 2 February 1908
John Xavier Merriman, 3 February 1908 – 31 May 1910