Mr. Fonseka is a Fellow of the Institute of Chartered Accountants of Sri Lanka, and Fellow of The Chartered Institute of Management Accountants of UK, and holds an MBA from the University of Sri Jayawardenepura.

Mr. Fonseka is the Joint Managing Director of Mackwoods (Pvt) Ltd., and Managing Director of Mackwoods Plantations (Pvt) Ltd., and functions as a Director of several companies of the Mackwoods Group.

He was a Past President of the CIMA, Sri Lanka Division, and was a Member of the Developing Nations Committee of the International Federation of Accountants (IFAC). He has served on the Urgent Issues Task Force of the Institute of Chartered Accountants of Sri Lanka; and is presently a member of the International Development Committee of CIMA Global. He is a member of the ACTOS Committee, and serves on the Chamber Committee of the Ceylon Chamber of Commerce.