Muhoroni MP Onyango K'Oyoo has won the ODM nominations with 18,669 votes.
His main challenger Ayiecho Olweny got 6,648 while Patrick Obora garnered 3,420 votes.
Returning officer Peter Otiang'a announced the results at Chemelil complex on Wednesday.
A presiding officer sustained serious injuries following a scuffle in one of the polling stations in Miwani ward.
Otiang'a said the PO has been admitted to Jaramogi Oginga Odinga Teaching and Referral Hospital.
K'Oyoo thanked Muhoroni constituents for having faith in his leadership and for handing him the mandate to fly ODM's flag.
In the 2013 polls, K'Oyoo was denied the ODM ticket and opted for People's Democratic Party (PDP) through which he won the seat.
At that time, Prof Olweny was handed the certificate but lost in the March 4, 2013 general election.
K'Oyoo also hailed ODM for the free and fair exercise.
"I am happy that I have won the ticket despite various challenges during nominations," he said.
He said voting started late in most of the polling stations due to delays in distribution of voting materials.
