Ukil Abdus Sattar Bhuiyan, one of the seven BNP lawmakers who recently resigned, has won the Brahmanbaria-2 by-election as an independent candidate.
He bagged 46,323 votes while his nearest rival Jatiya Party candidate Abdul Hamid Bhasani polled 9,580, according to unofficial results.
Sattar got the backing of Awami League during his campaign.
Meanwhile, the ruling party-led 14-party alliance candidate AKM Rezaul Karim Tansen won the Bogura-4 constituency by-polls by a slim margin.
He defeated his nearest rival independent candidate Ashraful Hossain Alam, widely known as Hero Alam, by 834 votes.
According to unofficial results, Tansen got 20,405 votes while Alam bagged 19,571.
However, the results of the by-polls in four other parliamentary seats were not available till filing the report at 9:00pm.
The seats fell vacant following the resignation of BNP lawmakers in December last year.
The constituencies are Thakurgaon-3, Bogura-4 and Bogura-6, Chapainawabganj-2, Chapainawabganj-3 and Brahmanbaria-2.
Voting started at 8:30am and continued till 4:30pm without any break.