National Assembly Speaker Justin Muturi on Wednesday declared the Kibra constituency seat vacant.
The key announcement sets the ball rolling on the by-election to find a replacement for the Late Ken Okoth.
"In pursuance of the provisions of section 16 (3) of the Elections Act, 2011, I command you that, due notice being given, you do cause election to be held according to law of a member of service in the National Assembly for the said constituency," the notice from Muturi read in part.
With the official announcement, IEBC is now constitutionally mandated to conduct a by-election within the next three months.
ODM politicians eyeing Kibra seat
Earlier in the week a number of politicians from the Orange Democratic Movement (ODM) party were reported to be eyeing the parliamentary seat.
Among these are former nominated senator Elizabeth Ongoro, Secretary-General Edwin Sifuna, former presidential campaign manager Eliud Owalo and ODM youth leader Benson Musungu.
The late MP's brother, Imran Okoth, is also said to be in the running for the seat.
Mr Owalo on Tuesday announced that he had officially relinquished his membership to the ODM party stating that his "enthusiasm has waned".