Mlangeni’s funeral service will be held on Wednesday at the Soweto campus of the University of Johannesburg.
In his tribute, Ramaphosa described the fallen icon as a "beacon of ethical leadership and care for humanity" whose death marked the end of a generation of history and left the future in the hands of those who remained.
"With his passing, Mlangeni has indeed passed the baton to his compatriots to build the South Africa he fought to liberate and to reconstruct," Ramaphosa said.
Mlangeni championed the values needed to do this, including dignity and opportunity for all, and his "dramatic life was a unique example of heroism and humility inhabiting the same person," Ramaphosa said.
On his part, senior ANC member Tokyo Sekgwale shared his memories of the late Mlangeni, saying he should not just be remembered as someone who spoke out against former President Jacob Zuma’s corrupt administration but as a principled man and fighter for justice.
ANC treasurer-general Paul Mashatile said even in his last days, Mlangeni dedicated his time to ensuring an ideal South Africa could be achieved.
Mlangeni was the last Rivonia treason trialist, and jailed alongside Nelson Mandela in 1964 after a treason trial.
He died at the age of 95 following abdominal complaint at Pretoria’s Military Hospital, according to his family.
Mlangeni, who spent 26 years in jail and was the last of the eight defendants in the trial to die, had been admitted to hospital following an abdominal complaint.