Dimple Yadav won Mainpuri with a margin of over 2.88 lakh votes.
Akhilesh Yadav's Samajwadi Party won in his father Mulayam Singh Yadav's Mainpuri constituency in Uttar Pradesh. Akhilesh Yadav's wife Dimple Yadav defeated her rival, BJP's Raghuraj Singh Shakya, by a margin of over 2.88 lakh votes.
Results will also be declared today for bypolls in five assembly constituencies in five states.
Mainpuri was vacant after the death of her father-in-law and Samajwadi Party founder Mulayam Singh in October.
After the win, Dimple Yadav thanked Mainpuri voters for supporting her.
"I want to thank everyone who has supported me. I said this would be a historic mandate in the name of Neta ji and that is what has happened," she said.
Though the outcome of the bypolls would not make much difference to the government at the Centre as well as in Uttar Pradesh as the BJP has a comfortable majority at both the places, a win would give psychological advantage to the winner in the run-up to the 2024 general election.
Voting was held on December 5 in six assembly seats in Bihar, Chhattisgarh, Odisha, Rajasthan and Uttar Pradesh and in the Mainpuri Lok Sabha seat.