Light middleweight Phindile Mwelase, 31, fell into a coma on October 10 after a fight against Liz Butler, who defeated her by a knockout. She died on Saturday at a Pretoria hospital.
South Africa President Jacob Zuma expressed his "heartfelt condolences on the untimely death" of Mwelase.
His office said in a statement on Tuesday. "She joined a sport that is predominantly male, and was proving that women can also succeed in boxing.
"Her untimely passing has robbed us of a role model."
In a statement on their website Boxing South Africa added: "Boxing SA not only grieves at the passing of a wonderful and tremendous individual but also for the loss her family suffers. Our hearts and prayers go out to them at this difficult time."
Mwelase is the third athlete to die in sports-mad South Africa in less than a week. National soccer goalkeeper and captain Senzo Meyiwa was shot dead by intruders at his girlfriend's home on Sunday night.
Former world 800 metre champion Mbulaeni Mulaudzi was killed in a car crash on Friday.
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