Mariga is among the aspirants facing the Jubilee Party National Elections Board on who will be issued with the party's ticket.
Jubilee candidate will be battle it out with candidates from ODM, ANC, and Ford-Kenya on November 7.
The campaign period for the by-elections run through Monday, September 9 to Monday, November 4.
The seat fell vacant after the death of Ken Okoth on July 26 after a battle with cancer.
Through a statement on Monday 26, Jubilee party secretary-general Rafael Tuju confirmed Macdonald Mariga, Morris Peter Kinyanjui, Walter Trenk, Said Ibrahim and Doreen Wasike as other aspirants.
Kinyanjui was a Kibra MP aspirant in 2017 while Ibrahim was the TNA candidate in 2013.
ODM will conduct its party nominations on Saturday 7.
Amani National Congress party picked Eliud Owalo as its candidate for the upcoming Kibra by-election.
Owalo was former ODM leader Raila Odinga's aide and was also in NASA's secretariat in the run-up to the 2017 election.
