Olusegun Ajayi was born on 12^th June, 1966 in Samaru-Zaria, Kaduna state. He hails from Esa-Oke in Osun state. He attended public primary and secondary schools in Saidu Primary School Zaria, Kaduna State and Government Secondary School Funtua, Kastina state.

He graduated with a B.Sc degree in Quantity Surveying from the Ahmadu Bello University Zaria in 1988. He also holds a M.Sc Degree in Project Management Technology from the Federal University of Technology Owerri in 2005.

He is a corporate member of the Nigerian Institute of Quantity Surveyor (NIQS) and a Registered Quantity Surveyor with the Quantity Surveyors Registration Board of Nigeria (QSRBN).

Olusegun Ajayi is a Chief Lecturer in the Department of Quantity Surveying of Federal Polytechnic Nekede. He had served as the Head of Department of Quantity Surveying (2009-2014) and Dean, School of Environmental Design and Technology (SEDT) (2017-2019). He had also served as Deputy Director, Polynek Consults Ltd, Deputy Director, Centre for Intellectual Property Transfer (CIPT), Director, Technological and Entrepreneurship Development Centre (TEDC) and Ag. Director, Physical Planning Unit (PPU).

He is a member of the Academic Board and had served in several committee including Admission and Entrance Committee, Polytechnic Book Review Committee, Plagiarism Test Services Committee, Staff Disciplinary Committee, Infectious Disease Control and Monitoring Committee and Chairman 46^th Matriculation Committee of the Federal Polytechnic Nekede.

Olusegun Ajayi has published two textbooks, Principles of Construction Economics and Introduction to Quantity Surveying. He has also published several articles in Journals and presented papers in seminars and conferences.

He had also served as an adjunct lecturer in the Department of Quantity Surveying at the University of Uyo and Federal University of Technology Owerri. He is an external examiner to the Akanu Ibiam Federal Polytechnic Unwana, Federal Polytechnic Oko, Akwa Ibom State Polytechnic Ikot Osuara and Abia State Polytechnic. He had also served as an NBTE resource person for the accreditation of ND/HND Quantity Surveying programme for Federal Polytechnic Oko, Akanu Ibiam Federal Polytechnic Unwana and Lagos state polytechnic Ikorodu, Lagos state.

Olusegun Ajayi is a member of the 15^th Governing Council of the Federal Polytechnic Nekede and currently the Director, Monitoring and Evaluation Unit (M&EU). He is an ordained Reverend Minister at the Foursquare Gospel Church in Nigeria.