The rebel TMC faction led by Ritabrata Banerjee took control of Trinamool Bhawan on the EM Bypass in Kolkata on Friday.
The takeover occurred 24 hours after the dissident camp staked its claim over the party name and symbol before the Election Commission.
New posters outside the building identify senior MLA Arup Roy as the party chairperson, omitting Mamata Banerjee.