In 1966, Botha was appointed a law advisor in South Africa's Department of Foreign Affairs; during 1966–1974 he attended annual sessions of the United Nations (UN) General Assembly. In 1974, a month after presenting his credentials as ambassador to the UN, South Africa was suspended from the body.
Botha's interest in public life mixed diplomacy with politics, and he won a seat for the ruling National Party in April 1970 and again in May 1977. In 1975 he was appointed ambassador to the United States, combining this post with that of permanent representative at the UN, even though apartheid South Africa had been suspended from fully participating in its meetings and activities.
In April 1977, with his popularity high among white South Africans because of his combative diplomatic style, Botha was appointed minister of foreign affairs. Twice a candidate for the presidency, Botha was on the verligte (enlightened) end of the political spectrum. In February 1986 he suggested that South Africa could one day be ruled by a black president.
Botha was instrumental in bringing about the 1984 Nkomati Accord, a nonaggression pact between South Africa and Mozambique that brought him into conflict with South Africa's military and its policy of regional destabilization. Along with U.S. emissary Chester Crocker, Botha ignited a process of dialogue that would eventually prepare the way for the cessation of hostilities in Angola and the independence of Namibia.
When apartheid ended in 1994, Botha became minister of minerals and energy affairs in the government of national unity headed by President Nelson Mandela. In 1996, Botha resigned from government and public life after F. W. de Klerk quit South Africa's postapartheid national unity government.
Crocker, Chester A. High Noon in Southern Africa: Making Peace in a Rough Neighborhood. New York: Norton, 1992.; Pottinger, Brian. The Imperial Presidency: P. W. Botha, the First 10 Years. Johannesburg: Southern Books, 1988.