The tribunal, in a ruling delivered on Monday, upheld the decision of the Mombasa County Returning Officer who had rejected Sonko's clearance for the gubernatorial tussle.
According to the tribunal, Sonko failed to submit his original degree certificate as well as a certified copy of the same, in breach of article 75 of the Kenyan constitution.
Meanwhile, Sonko will be headed back to the court tomorrow to appeal the tribunal's decision to throw out his bid.
Elsewhere, the Wiper Party has been granted the green light to nominate another candidate for the Mombasa seat.
The papers for the new nominee are expected by the county returning officer within 72 hours and are in compliance with election regulations by the commission.