Marakwet East MP Kangongo Bowen becomes the third MP to be reinstated bu Court of Appeal in as many months following Thursday's land mark victory.
In March Justice Kanyi Kimondo nullified Bowen's victory following a petition launched by a voter, Sammy Kemboi.
And the Jubilee rebel MP, who at one time was dropped from parliamentary environmental committee after defying the party position, appealed the decision.
Appellate Judges Erastus Githinji, Fatuma Sichale and Hannah Okwengu reversed the High Court decision.
In their ruling at Eldoret on Thursday, they noted that elections were free, fair and verifiable thus giving the first term MP a lifeline.
On Wednesday, Bowen's comrade, Alfred Keter, also survived in the same court after having High Court nullifying his victory earlier.
Last month, Embakasi East MP Babu Owino, became the first MP to challenge a High Court ruling successfully at the appeals court.