A 1989 BSc holder in International Relations from Obafemi Awolowo University, Ile-Ife with a Masters in International Law and Diplomacy (MILD) from the University of Lagos in 1997, Olusegun Adeniyi began his journalism career as a Staff Reporter with 'The Guardian' newspaper of Nigeria in December 1990. In April 1992, he left 'The Guardian' to join the 'African Concord' magazine as a Senior Staff Writer and in September of the same year, he was appointed the magazine's Abuja Bureau Chief with accreditation to cover the State House.
Adeniyi joined THISDAY newspaper in January 1999 as Deputy Editor of the Saturday newspaper before he later became editor of the Sunday THISDAY; and in August 2005, he was appointed the editor of THISDAY title. On 30th May, 2007, he was appointed by the late President Umaru Musa Yar'Adua to be his Special Adviser on Media and Publicity, a position he occupied until Yar'Adua died on 5th May, 2010.
Adeniyi has attended and participated in several professional and academic programmes in many countries. Notably, in July 2007, he attended the International Visitor Leadership Programme organised by the US State Department. He also attended the Chinese government-sponsored 'Seminar on Press and Publications in Developing Countries' in Beijing in April 2012. He spent the 2010/2011 academic session as a Fellow at the Weatherhead Centre for International Affairs, Harvard University where he conducted his research on the factors that shape incumbent presidential elections in Africa. He is also a Senior Fellow of the Nigeria Leadership Initiative (NLI) and a founding member of the National Stakeholder Working Group of the Nigeria Extractive Industry Transparency Initiative (NEITI).
Adeniyi has delivered speeches in several countries, including in August 2016 at the China-Africa Public Diplomacy Forum which held in Tanzania and is the author of five books: The Last 100 Days of Abacha; Abiola's Travails; Fortress on Quicksand; POLITRICKS: National Assembly under Military Dictatorship and Power, Politics and Death: A front-row account of Nigeria under the late President Yar'Adua.
Adeniyi, who, for the second year, is a member of the Panel of Judges for the Nigeria Breweries Plc 'Maltina Teacher of the Year 2016', was recently appointed a member of the advisory board for the Africa Initiative for Governance (AIG), founded and chaired by Mr. Aigboje Aig-Imoukhuede, with a focus on partnering with leading academic institutions in the world for the award of post-graduate scholarships to outstanding Nigerians and Ghanaians who are expected to come back and work in their respective country's public sector as change agents.
Married with three children, Adeniyi is currently the Chairman of THISDAY Editorial Board and writes a weekly column, 'The Verdict'.