Keoshu filed his papers in the presence of B Henok Buchem, ADC and returning officer for the 58 Shamator-Chessore Assembly Constituency by-election.
According to reports, official sources confirmed that no other candidates filed nomination papers for the upcoming by-elections.
ALSO READ: At least 100 killed in suicide blast at a Afghanistan mosque
The by-election in Nagaland is scheduled for October 30.
Nominations will be scrutinised on October 11, with the deadline for withdrawals on October 13.
The vote will be counted on November 2.
The seat became vacant following the death of MLA and adviser Toshi Wungtung, necessitating the by-election.
Though the NPF had planned to field a candidate, the party decided to withdraw from the race and agreed to support the NDPP candidate as requested by the latter.