Hashim Amla resigned as South Africa captain at the end of the second Test against England at Newlands on Wednesday.
AB de Villiers will lead the team in the remaining two Tests of the series.
"This decision is not an easy one but the more I think about it the more I believe I can be of greater value to the Proteas as a fully-focused batsman and senior player at this time of rebuilding our team," said Amla.
According to a Cricket South Africa statement, Amla decided to step down before the second Test. He told his teammates about his decision at the end of the match.
"I felt someone else could do a better job," he told journalists, adding that he had been thinking about resigning for several weeks.
Amla captained South Africa in 14 Tests, winning four, losing four and drawing six.
The second Test ended in a draw, leaving England 1-0 up in the four-match series with the next Test to start in Johannesburg on January 14.