The winner of the presidency of the ruling party would be a strong favourite to succeed Mr Zuma as president after the presidential elections in 2019.
The ANC has won every election since the end of apartheid in 1994.
Dr Dlamini-Zuma has held three Cabinet positions before heading to Addis to take up the AUC chairmanship. In 1994, Nelson Mandela appointed her Health minister.
She was then named Foreign Affairs minister after former President Thabo Mbeki took office in 1999, a post she held for a decade.
In 2009, Dr Dlamini-Zuma was reassigned to the Home Affairs ministry.
She is credited for overseeing a successful overhaul of the system used in issuing identity documents, passports and birth certificates.
She was elected chairperson of the AU Commission in July 2012. Nic Borain, a political analyst says Mr Zuma is likely to position her at the centre of ANC politics.
“Those running her campaign, and it’s widely speculated that Jacob Zuma is backing her, would probably try and move her into a more central role in politics before the party’s elective conference,” he said.
A politics professor at the University of Witwatersrand, Susan Booysen, says a Cabinet post would be massively beneficial for her campaign “because she could get a position that would push her into the limelight”.
Dr Dlamini-Zuma, 67, was married to President Zuma, 74, but divorced in 1998 and they have four children together.
At the AU, Ms Zuma handed over to Mr Moussa Faki Mahamat. Dr Mahamat of Chad was elected on January 30. The 56-year-old is father of five. Ms Zuma was the first woman to lead the bloc of 54 states. She declined to seek a second term in office after completing a four-year tenure.