Isiaka Adetunji Adeleke was born in 15 January 1955 in Ede in Osun State. He holds a Bachelor Of Arts Degree, and a Master's Degree In Public Administration. He was Chairman, Governing Council, Nigerian Export Promotion Council, Pro-Chancellor And Chairman, Governing Council, University of Calabar, Nigeria. He was first civilian Executive Governor Of Osun State (1992–1993), until the military government aborted the transition to full civilian administration. As governor, he signed the law establishing the Osun State College of Technology.
Alhaji Isiaka Adetunji Adeleke was elected senator for Osun West in 2007. His main competitor was Mudasiru Oyetunde Hussein, standing for the Action Congress. Hussein had spent two terms in the House of Representatives (1999–2007) as a member of the Alliance for Democracy party in a Lagos State constituency, but originated from Osun state. Hussein appealed the election unsuccessfully. Isiaka Adetunji Adeleke was appointed to committees on Upstream Petroleum Resources, Integration and Cooperation, Housing and Air Force.
In March 2008, he instituted a scholarship award for about 100 indigent students in tertiary institutions across the country.
In July 2009, as chairman of the Senate Committee on INEC, Senator Isiaka Adetunji Adeleke praised the work of the Independent National Electoral Commission, saying "so far INEC has performed creditably well". He has supported the rights of Nigerians living abroad to vote in Nigerian elections.