Mimiko said he resigned his PDP membership based on "some well thought-out personal reasons".
Mimiko was said to have announced his resignation from the party in a three-paragraph letter addressed to the PDP Chairman, Ondo West Local Government Area.
The immediate former governor said in the letter that he left the PDP based on personal reasons.
"I hereby with utmost humility inform you of my decision to resign my membership of the PDP with effect from today, June 13, 2018 for some well thought-out personal reasons", Daily Independent quoted Mimiko as saying in the letter.
"It was an honour working with the many prominent Nigerians with whom I shared the PDP platform for the entire period I was in there as a member."
According to the newspaper, Mimiko and his supporters may be returning to the Labour Party (LP), on which platform he won governorship elections in 2007 and 2012.
He had defected to the PDP in 2003 when he was allegedly deprived of participating in the gubernatorial shadow election of the Alliance for Democracy (AD).
Mimiko then dumped the PDP for LP in December 2006 to pursue his governorship ambition when he realised he could not clinch the PDP ticket.
On October 2, 2014, he again led his followers back to the PDP.