Haryana Chief Minister Nayab Singh Saini won the Karnal Assembly bypoll defeating his Congress rival Tarlochan Singh.
According to the Election Commission data, Saini won by a margin of 41,540 votes.
Karnal seat was earlier held by BJP's Manohar Lal Khattar. In the 2019 Assembly polls, Khattar defeated Tarlochan Singh by a margin of over 45,000 votes.
The counting of votes for the Karnal assembly seat began at 8 am along with the votes for the 10 Lok Sabha seats in the state.
Polling for all 10 Lok Sabha seats and the Karnal assembly constituency was held in the sixth phase of the general election on May 25.
Chief Minister Saini is the outgoing MP from Kurukshetra and the state BJP chief. He was sworn in as the chief minister on March 12, replacing Khattar whose resignation as MLA from Karnal necessitated the by-election.
Khattar was fielded by the BJP from the Karnal parliamentary seat from where he is leading by a margin of more than 2.3 lakh votes.