Tunji started as a teacher in 1983, before going into broadcasting as a Presenter/Announcer in the then Television Service of Oyo State. He later joined Seven Up Bottling Company Plc in 1989, as Personnel Assistant. He managed the HR Departments in Ilorin, Ibadan, Kaduna, and Aba Plants. He was a part of the Seven Up Enterprise Transformational Program handled by Accenture Consulting as a counterpart staff where he worked on Strategy, Processes, Technology Initiatives and Human Capital Review Projects. Before leaving in 2000, he was the Manpower Planning Manager for Seven Up Bottling Company Plc. He later worked for Nigerian Bottling Company Plc as Planning Manager, Global Energy Nigeria Limited as Head HR Department and Niger Dock Plc as Manager-HR during the company's transition from government parastatal to a private sector led enterprise.
Tunji is currently the Managing Partner of New Concepts Consulting.