He said his decision to quit the APC was after wide consultation and has been accepted by his followers.
An ally of former Osun governor, Rauf Aregbesola, who served as the commissioner for finance in his government, has defected to the Peoples Democratic Party.
Wale Bolorunduro, a member of the All Progressives Congress, announced his defection while speaking with journalists in Osogbo on Wednesday.
He described the APC in Osun State as leadership of "deceit, injustice, lack of fairness, unhealthy/needless rivalry and poor reward system that are aliens to what Awolowo stood for.".
He said his decision to quit the APC was after wide consultation and has been accepted by his followers.
"I have consulted wisely and widely with my followers, admirers, friends, and families, who felt we should pitch our tent with PDP, to join this party and to work with them to shine the light (Imole Osun)," said Mr Bolorunduro.
"We would have done this before the 2022 gubernatorial election, but knowing them it was better to err on the side of caution for us to have today, tomorrow and future.
"My records are there in Zenith Bank, where I pioneered different financing groups (upstream oil and gas, telecom, power sector, infrastructure group) at different times when God allowed me to conquer one front after another. My adrenalin is usually fired by new challenges."
Mr Bolorunduro's defection is the first high-profile defection from the APC to the PDP after the latter won the governorship election in the state.
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Before the election, Kolapo Alimi, a two-term commissioner during Mr Aregbesola's administration, defected to the PDP.
Mr Alimi, who defected in June, was reportedly appointed the Deputy Director-General of Adeleke Campaign Organisation.
Mr Aregbesola, the current Minister of Interior, has been at loggerheads with Governor Gboyega Oyetola, leading to divisions in the state chapter of the APC.
Ahead of the July 16 governorship election, The Osun Progressives, the faction of the party loyal to Mr Aregbesola, reiterated their support for the APC; though they remained silent on supporting Mr Oyetola.
On the eve of the election, Mr Aregbesola jetted out to Germany to attend a conference, scheduled two days after the election.
Mr Oyetola eventually lost his re-election bid to Ademola Adeleke, the PDP candidate, who polled 403,371 votes against his 375,027 votes.
Oladele Oluwabamji, the director of media and publicity of PDP in the state, confirmed the defection of the ex-finance commissioner.
