The High Court in Kerugoya has for the second time dismissed a petition filed by Nark-Kenya leader Martha Karua against the election of Governor Anne Waiguru.
While delivering the judgement on Thursday, Justice Lucy Gitari said the election was free and fair.
Justice Gitari said the evidence produced by Ms Karua was hearsay, contradictory and unreliable.
The judge added that the claims by Ms Karua that the election was marred by illegalities and irregularities such as voter bribery and exclusion of her agents from polling stations are unsubstantiated.
Following the verdict, Ms Karua said she will appeal the decision.
"We are determined to pursue justice to the last mile," she said outside the court.