West Bengal Chief Minister Mamata Banerjee won the Bhabanipur Bypoll with a record margin of 58,832 votes.
She defeated her BJP rival Priyanka Tibrewal. Banerjee got 82,000 votes, while over 25,000 votes were polled to Tibrewal.
Banerjee thanked her supporters from Bhabanipur for their support. Her supporters celebrated her victory outside her residence.
"Around 46 percent of people here (in Bhabanipur) are non-Bengalis. They all have voted for me," she said. BJP candidate Priyanka Tibrewal has conceded defeat.
Her party Trinamool Congress (TMC) is also leading from Samserganj and Jangipur assembly constituencies.
Kolkata seat registered 57% voter turnout amid tension between the TMC and BJP camps.