The High Court had upheld the election of Cornel Rasanga as Siaya Governor.
The petitioner former Rarieda MP Nicholas Gumbo has been ordered to pay Sh3 million in costs.
Gumbo's petition was dismissed on grounds that it lacked evidence to warrant a nullification of the August 2017 poll.
Meanwhile, former Gem Member of Parliament Jakoyo Midiwo was also ordered by the same court ordered to pay Sh3 million in costs after his petition against MP Elisha Odhiambo was dismissed.
Presiding Judge Esther Maina said Midiwo did not provide sufficient evidence to overturn Odhiambo's win.
The Judge noted that the election was conducted in a free and fair manner.
"There was no iota of evidence that there were irregularities during and after the election. There was no evidence that the respondent interfered with the process," said justice Maina on Monday while delivering the ruling.