In a cliffhanger contest, the BJP candidate received 76,648 votes against JD(U)'s 73,016.
The BJP on Thursday won from Bihar's Kurhani assembly seat where its candidate Kedar Prasad Gupta defeated Manoj Singh Kushwaha of Chief Minister Nitish Kumar's JD(U) by 3,645 votes.
In the cliffhanger of a contest, Mr Gupta polled 76,648 votes while Kushwaha finished with 73,016 votes.
The election was necessitated by the disqualification of RJD MLA Anil Kumar Sahani.
The RJD is a constituent of the Mahagathbandhan.
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