The oath of office and secrecy to Mamata was administered by Governor M K Narayanan on the Raj Bhawan lawns at 1:01pm, a time chosen by the Trinamool Congress chief.
Union home minster P Chidambaram and finance minister Pranab Mukherjee were among the central leaders who attended the swearing-in.
The swearing-in took place in the presence of 3200 invitees drawn from among the top names in politics, business and art and culture.
Left Front leaders, including Bhattacharjee and Bose, attended the ceremony at Raj Bhavan. The huge guest list included former chief minister Buddhadeb Bhattacharjee who was invited along with wife Meera by deputy leader of the Trinamool Congress Legislature Party Partha Chatterjee who personally went to their Palm Avenue residence, the first visit by any Trinamool leader there since the party came into existence in 1998.
Also invited were CPI(M) state secretary Biman Bose, CPI state secretary Manju Kumar Majumder, RSP leader Kshiti Goswami and Forward Bloc state secretary Ashok Ghosh.
Ahead of her shift from New Delhi to Kolkata, Mamata resigned as railway minister on Thursday.
Trinamool Congress will have 36 ministers but the number of Congress ministers has not been disclosed.
A list of the 36 Trinamool Congress ministers were received by the chief secretary's office from the Raj Bhavan, sources in the Writers'Buildings, the state secretariat, said.
Trinamool Congress ministers' list includes the name of former FICC Secretary General Amit Mitra, party leader Partha Chatterjee, former state Home Secretary Manish Gupta, MLAs Subrata Mukherjee, Abdul Karim Chowdhury, Sadhan Pandey, Upen Biswas, Sabitri Mitra, Bratya Basu, Madan Mitra and Noore Alam Chowdhury.
Congress, which had fought the assembly polls in alliance with TC, also decided to join the government.
"We are going to join the government. We have conveyed this to the Hon'ble chief minister. You will get to know who from Congress will be joining the government," AICC observer in-charge of West Bengal Shakeel Ahmed said after a CLP meeting which took the decision of participating in the ministry.
Ahmed, who was flanked by defence minister A K Antony, said the names of Congress ministers had been communicated to Banerjee but did not disclose them to the media.
Antony said there was "a special gift" from Gandhi to Banerjee "which we handed over to her".
Trinamool Congress and allies Congress and SUCI had stormed to power in the state with a three-fourths majority signalling the historic changeover in the state's politics.
Source : ET