"She will meet with government, business, and civil society counterparts to discuss how to strengthen our bilateral relationship and address regional and global issues of concern, including deepening economic ties and advancing a just energy transition," it said.
Yellen is expected to push the government of President Cyril Ramaphosa to pursue its fledgling transition to cleaner energy and away from a heavy reliance on coal. South Africa has been promised $8.5 billion from rich nations to help, but most of that is in loans, not grants, and the country is dealing with an energy crisis that risks curbing economic growth.
While the US is among countries backing the project, authorities may ask the US for additional financial support.
Yellen arrives a day after South Africa hosted Russian Foreign Minister Sergei Lavrov and foreign minister Naledi Pandor deflected criticism of joint military drills planned with Russia and China, saying that hosting such exercises with "friends" was the "natural course of relations".
Additional reporting by Bloomberg.

Janet Yellen, chair of the U.S. Federal Reserve, speaks during a news conference following a Federal Open Market Committee (FOMC) meeting in Washington, D.C., U.S., on Wednesday, June 14, 2017. Federal Reserve officials forged ahead with an interest-rate increase and additional plans to tighten monetary policy despite growing concerns over weak inflation.