The Constitution of South Africa is the supreme law of the Republic of South Africa. It provides the legal foundation for the existence of the republic, it sets out the rights and duties of its citizens, and defines the structure of the Government. The current constitution, the country's fifth, was drawn up by the Parliament elected in 1994 in the South African general election, 1994. It was promulgated by President Nelson Mandela on 18 December 1996 and came into effect on 4 February 1997, replacing the Interim Constitution of 1993. The first constitution was enacted by the South Africa Act 1909, the longest-lasting to date. Since 1961, the constitutions have promulgated a republican form of government.

Since 1996, the Constitution has been amended by seventeen amendment acts. The Constitution is formally entitled the "Constitution of the Republic of South Africa, 1996." It was previously also numbered as if it were an Act of Parliament—Act No. 108 of 1996—but, since the passage of the Citation of Constitutional Laws Act, neither it nor the acts amending it are allocated act numbers.