Gatundu North parliamentary seat was on Wednesday declared vacant over violation of election laws.
Justice Weldon Korir ordered the Independent Electoral and Boundaries Commission (IEBC) to conduct fresh elections.
“I declare that the seat of the MP Hon Anne Wanjiku has become vacant,” Korir ruled.
Justice Korir directed the Deputy Registrar to forward the ruling to the Speaker of the National Assembly for appropriate action.
In February, the sitting MP Annie Wanjiku Kibe was dragged to court by her predecessor Clement Waibara on grounds that she did not qualify to vie for the seat in 2017.
In a petition filed in the court of Appeal, Waibara argued that Kibe had not resigned as a nominated member of the Kiambu county assembly (MCA) when she ran for the seat.
In court documents, Waibara said that IEBC participated in committing a constitutional illegality by allowing Kibe to vie for the MP seat while she was still serving as a ward rep.
“Even though she had the option to resign, there is no evidence that she did so prior to or after her nomination (by the Jubilee Party). In the circumstances, Ms Wanjiku was as at the date of her nomination still a sitting MCA enjoying attendant monetary and non-monetary benefits,” he said.