Sikkim Chief Minister Prem Singh Tamang aka PS Golay won the by-poll to the Poklok Kamrang Assembly seat by 8,953 votes.
The Sikkim Krantikari Morcha (SKM) founder defeated his nearest rival Moses Rai of the Sikkim Democratic Front, an election official said.
While Golay registered 10,811 votes, Rai polled 1,858 votes.
The SKM supremo secured 84 per cent of the 12,870 votes polled in the seat on October 21.
Yadhu Kumar Rai of the Sikkim Republican Party stood third with 125 votes while 76 none of the above (NOTA) votes were polled.
The SKM’s alliance partner, BJP too opened its account in the state, with its candidate Sonam TSH Venchungpa winning from Martam Rumtek Assembly seat by defeating his nearest rival Nuk Tshering Bhutia of the SDF by 6,150 votes, he said.
Venchungpa polled 8,204 votes while Bhutia secured 2,054 votes.
Nima Lepcha of the Hamro Sikkim Party stood third with 1,235 votes.
Some 154 NOTA votes were polled.
The counting of votes for the Gangtok Assembly seat is underway.