Former parastatal boss Fernandes Barasa is the Kakamega governor-elect.
The ODM candidate got 192,929 votes while ANC's Cleophas Malala garnered 159,508 in an election marred by poor turnout.
In the race where 43 per cent of the 844,551 registered voters cast their ballot, UDP's Cyrus Jirongo got 5,974 votes, Mike Osundwa 1,146, Suleiman Sumba 1,078, Samuel Omukoko 761 and Austin Opitso 150.
Announcing the results yesterday at the Kakamega High School, Returning Officer Joseph Ayatta said the elections were free and fair.
"We had a lower turnout than anticipated as about 361,546 cast their ballots. No candidate was found doing any irregularity," he said.
In his victory speech, Mr Barasa said he would ensure that his campaign pledges were fulfilled.
"This is not my victory, it's that of the people of Kakamega. I congratulate my competitors for giving their all. I will work with them to ensure that we take Kakamega forward," said the former Ketraco CEO.
He thanked the voters for being patient even as the election was postponed twice.
Speaking separately at the Golf Hotel, Mr Malala conceded defeat.
"We lost with about 29,000 votes. It's painful and if this kind of pain is what Raila Odinga has been going through all the times he's lost elections, then he's a strong may. It's painful to lose but I accept it.
"We did all we needed to do. We campaigned well but the Lord's will was done. I congratulate Barasa and his deputy Ayub Savula," he said.
The former Senator thanked his party leader Musalia Mudavadi and Kenya Kwanza leader William Ruto for campaigning and mentoring him.
He also thanked the IEBC for making the polls free and fair.
He challenged those who were elected to do the best for the good of county and the nation.
"If there's anything I can help you with in matters of governance, I will be more than available," he said.
Dr Beatrice Inyangala, his running mate, thanked him for giving a special platform for youth and women in politics.
The Kenya Kwanza regional coordinator and former Mumias East MP Ben Washiali said the police did not a good job in maintaining law and order.
"Malala is a young man and he will rise to his feet again," he said.
Kakamega Azimio la Umoja One Kenya Coalition leaders and their supporters celebrated Mr Barasa's victory in the streets for the better part of the afternoon.
Outgoing governor, Wycliffe Oparanya, thanked voters, saying they had redeemed his reputation by voting for Mr Barasa.
"Please accord him the support you gave me. This poll was difficult and full of bribery perpetrated by our opponents, but I am happy you were not swayed and stuck with us.
"We now have a full Azimio house in Kakamega as we have 10 out of 12 MPs in Kakamega and a super majority in the county assembly," he said.
Defence CS Eugene Wamalwa termed the poll outcome as a statement to Kenya Kwanza that Azimio was the people's choice in Western.
ODM Secretary-General Edwin Sifuna said the win for Azimio candidate raised their hope of more wins ahead, including in their case against Dr Ruto at the Supreme Court.
Other leaders present were MPs Tindi Mwale (Butere), Oku Kaunya (Teso North), Peter Sslasya (Mumias East), Beatrice Elachi (Dagoreti North) and Titus Khamala (Lurambi), and ODM regional elections coordinator Justus Kizito.