Botha died in "the early hours of the morning" at his home after an illness, his son, also named Roelof, told South Africa's eNCA news outlet.
Internationally, Botha was the most visible representative of apartheid at the height of protests and sanctions against the racist rule that ended with Nelson Mandela's election as the first black president in 1994.
Often willing to passionately debate critics, the longtime foreign minister was vilified around the world while drawing the ire of his own boss, President P.W. Botha, when he said in 1986 that South Africa might one day have a black leader.
"Merely because you are riding on a plane doesn't mean that you agree with the pilot's decisions," Botha said in a 1996 interview with peace advocate Padraig O'Malley.
Pik Botha, who was not related to the apartheid-era president, later served for two years as minister of mineral and energy affairs under Mandela, and said in 2000 that he would join the African National Congress, the ruling party that had led the movement against white minority rule for decades.
Botha was "one of the few" in the apartheid structure who realized "at an early stage that apartheid was a wrong and crime against humanity," the ANC said in a condolence message.
He will be remembered for "his support for South Africa's transition to democracy and for his service in the first democratic administration," the office of President Cyril Ramaphosa quoted him as saying. It said Botha's 17-year stint as foreign minister was "a world record in the diplomatic community."
Apartheid's last president, F.W. de Klerk, said Botha was a "unique and colorful personality" who advocated reform, constitutional negotiations and the release of Mandela from prison during intense discussions within the white minority government in the 1980s.
However, some South Africans are critical of Botha and other apartheid-era leaders who negotiated their own political exit in relative peace, saying their association with a system that denied basic rights to most of the population was unforgiveable.
In 1996, Botha dropped out of active politics after leaving Mandela's Cabinet when the National Party, the ruling party during apartheid, pulled out of South Africa's national unity government. He has said he opposed the party's decision.
He made few public comments after that, though said in some interviews that he felt remorse and was even haunted by apartheid's legacy while highlighting his efforts to change the system from within and oppose international communism.
Botha was "absolutely delighted" when Ramaphosa, a key ANC leader and negotiating counterpart during the transition to democratic rule in the early 1990s, became president in February, Botha's son said. Ramaphosa replaced Jacob Zuma, the scandal-marred president who resigned.
Botha, also a former South African ambassador to the United States, was foreign minister from 1977 until the end of apartheid in 1994.
He was involved in negotiations in the late 1980s that led to independence in neighboring Namibia and the withdrawal of Cuban troops from Angola, where South Africa had been involved in a conflict of Cold War proxies.
The reduction in regional tensions was followed by the 1990 release of Mandela, who had spent 27 years in apartheid prisons.
In the 1996 interview with O'Malley, Botha pondered the hard choices he made as apartheid's frontman.
"Now you can say to me, but I should have resigned and gone into the desert and isolated myself and shout and kick. That was one choice, yes," he said.
"The other one was to say the things I did say to change people's minds and to try and be a factor in the transformation that took place," Botha said. "Maybe I should have resigned and maybe I should have left politics, but I hung in there."
Follow Christopher Torchia on Twitter at www.twitter.com/torchiachris
Copyright 2019 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.