[3][4] Her career in banking goes back to June 1995, when she took up employment with Citibank Kenya, as a relationship manager, serving in that capacity for over six years.
She was then promoted to senior relationship manager, responsible for public sector enterprises, where she served for nearly two years, until 2003.
[3] She was further promoted to vice president, corporate banking at Citibank Kenya, where she served for nearly three years.
Starting in January 2006, and for the next six and half years, Kilonzo served as the head of trade finance for the bank's customers in Kenya, Uganda, Tanzania and Zambia, at the level of director.
[3] In 2012, she was hired by Ecobank Transnational Incorporated as a senior group manager responsible for trade finance and based in Nairobi, Kenya's capital and largest city, serving in that role for four and half years.