Tennakoon currently serves as the Chief Financial Officer of Orient Finance PLC. He commenced his career as a Management Trainee at George Steuart & Co. Ltd and has over 15 years of experience in non-bank financial institutions including both managerial and senior managerial positions in The Finance Company PLC, Prime Finance PLC and HNB Finance PLC.

Tennakoon is a member of the Institute of Chartered Accountants of Sri Lanka and a member of the Institute of Certified Management Accountants of Sri Lanka. He holds a Bachelor of Business Administration Special Degree from the University of Colombo and an MBA Degree from the Postgraduate Institute of Management (PIM) of the University of Sri Jayewardenepura. He also holds a Diploma in Taxation from Sri Lanka Institute of Taxation while being a Certified Information System Auditor.