Awuondo earned his Bachelor of Commerce degree from Nairobi University in 1980.
Awuondo began his career as an audit senior at BDO Binder Hamlyn in 1980 and held it for four years. In 1985, he took a position of an audit manager at Githongo & Company in Nairobi.
A year later Isaac was appointed a group finance controller at Nation Group. Then in 1988 he was a finance director at Standard Chartered Bank. Since 1995 Awuondo has been a group managing director and director at Commercial Bank of Africa.
He also served as Director of Centum Investment Company Ltd. (also known as ICDC Investments Co. Ltd.) until September 12, 2008.
Awuondo is a chairman of the Kenya Conservatoire of Music and the Kenya Hospital Association and trustee of the Rhino Trust and Zawadi Africa Education Fund. He is a member of the Institute of Chartered Accountants in England and Wales, Institute of Certified Public Accountants of Kenya, Kenya Institute of Management.
On March 23, 1985 Isaac Awuondo married Beatrice Sidandi Musiga. They have 2 children.