"There is nothing fishy about this. If you do not resign, you lose your ministerial pension, it goes down really badly and if you are of age like me, you may as well leave parliament and create space for younger people," she said.
She turned 67 three days ago, on June 2.
"I am looking forward to claiming back my life and to enjoy life as an ordinary person," she added.
Mfeketo is a former Cape Town mayor. She was the deputy speaker of the National Assembly for five years between May 2009 and May 2014. Then president Jacob Zuma appointed her deputy minister of international relations and cooperation in 2014.
Ramaphosa appointed her the minister of human settlements in February 2018, a position she held until last week when the president announced a new executive.