High Court Judge Joel Ngugi on Thursday nullified the election of Gatundu North MP Wanjiku Kibe.
Ngugi cited massive irregularities in making the nullification.
Kibe's election had been challenged by former area MP Clement Waibara.
During the August 8 General Election, the IEBC declared Kibe as the winner after garnering 39,448 votes against Waibara who came in second with 9,296 votes.
Waibara later moved claiming that Kibe's election was not free and fair because she had allegedly used witchcraft to scare voters into voting for her.
However, Justice Ngugi did not find Kibe guilty of any electoral offence but stated that the IEBC made several errors that affected the credibility of the outcome.