Senator Olubiyi Fadeyi-Ajagunla won the Osun Central Senatorial seat for the PDP in February 2023, defeating nine-year incumbent and 9th Senate spokesperson Ajibola Basiru of the APC with 134,229 votes to 117,609. He was assigned as Chairman of the Senate Committee on Environment, and holds Vice Chairman positions on the committees on Communications and Trade and Investment. His identifiable legislative output includes SB.70, the Explosives Act (Repeal and Re-enactment) Bill. On constituency delivery his office has reported a wide spread of interventions -- road rehabilitation in Ikirun and Ila-Orangun, refurbishment of a 7.5 MVA transformer to end a protracted Ila-Orangun blackout, procurement of transformers for the Federal University of Health Sciences Teaching Hospital, annual N100 million bursary awards to approximately 1,500 students in the senatorial district, and a 5 km road secured under a presidential approval process in early 2026 -- though these claims come primarily from self-published sources and the senator's associates rather than from independent project monitors. A constituency road at Oduola Street, Oke Okanla, Osogbo attracted public complaints about an electricity pole left in the middle of the reconstructed carriageway; the senator attributed responsibility for pole relocation to the Ibadan Electricity Distribution Company, and the Osun State government subsequently relocated the pole. On integrity, Fadeyi resigned from the PDP on 12 July 2025 and defected to the APC, citing irreconcilable factional divisions in the party; the PDP filed suit in the Federal High Court in August 2025 seeking to vacate his seat under Section 68(1)(g) of the 1999 Constitution on the basis that no qualifying merger or division in the PDP justified the defection. That litigation was pending as of the date of compilation. He sought the APC ticket for re-election in 2027 but lost the APC senatorial primary for Osun Central in May 2026 to Adekunle Adegoke (SAN) by 13,138 votes to 26,655. No criminal charges or court convictions have been recorded against him.