The former governor was grilled by officers from the EACC at the Integrity Centre in Nairobi.
ODM, however, did not divulge further details about the case, including the reason for the arrest and whether his lawyers were already en route to seek his release.
"Our DPL Governor Wycliffe Oparanya has been arrested by officers from the DCI. Oparanya together with his wife Madam Priscillah are currently at the EACC offices at Integrity Centre," ODM said in a statement.
"No information has been given as to why they have been arrested & why they are being questioned," ODM, a party under the Azimio coalition, added.
Oparanya, who is also ODM's deputy party leader, served as Kakamega governor for two terms from 2013-2022.
He has supported opposition chief Raila Odinga consistently, backing him even after the August 2022 election loss, which saw some leaders shift allegiance.
This is the second time the former governor has been arrested this year. Oparanya, in July, was arrested after being accused of organising anti-government protests in Western Kenya.
On Wednesday, he was among the leaders missing as opposition politicians commemorated the 20th anniversary of the death of former Vice President Michael Wamalwa Kijana in Kitale, Trans Nzoia County.
The area governor, alongside Eugene Wamalwa, Kijana Wamalwa's brother and DAP-K party leader, renamed the Trans Nzoia County Teaching and Referral Hospital to the Wamalwa Kijana Teaching and Referral Hospital in honour of the deceased.
"At the late Vice President Michael Wamalwa's residence in Milimani Kitale, paying our respects before the Holy Mass. Joining the family in celebrating the life of this great leader, who steadfastly championed democracy, ensuring a level playing field in politics," Natembeya stated.
George Wajackoyah, Roots Party leader and 2022 Presidential candidate and his Usawa kwa Wote Party counterpart Mwangi wa Iria were also present at the event.
The timing of Oparanya's recent arrest also comes ahead of President William Ruto's Western Kenya tour from August 27-30.
More to follow... By Edwin Austin, Kenyans.co.ke