High Court sitting in Malindi on Friday nullified Debaso MCA Emmanuel Changawa's victory after months of battle.
The case had been filed by ANC's Dickson Karani who had earlier lost in a lower court.
Justice Weldon Korir noted that the elections were marred with illegalities and irregularities thus declaring the outcome null and void.
“The evidence that was brought before this court was enough to nullify the election," he said.
Kilifi was the only county that elected ODM leaders from the ward to National level.
Apparently, the MCA lost his seat when ODM leader Raila Odinga was in the county for a secret meeting with President Uhuru Kenyatta.
However, he can still challenge the outcome at the Appeals Court if not satisfied with the ruling.