More than 6,675 eligible voters in the Keetmanshoop Rural Constituency are expected to cast their ballots on May 15.
The by-election was necessitated by the expulsion of former LPM Councillor Gerrit Witbooi.
The Electoral Commission of Namibia (ECN) says the supplementary registration was completed this month.
Candidates who will contest the by-election are Johannes Eiman of the PDM, Elias !Kharuxab of the Swapo Party, Willem Labuschagne for the LPM, Magdalena van Staden of the IPC, and Gerrit Wibooi, an independent candidate.
ECN will deploy election officials a day prior to the election date.