Senior Janata Dal (United) leader Nitish Kumar was sworn-in as the Bihar Chief Minister on Sunday.
He was administered the oath of office and secrecy at the Raj Bhawan in Patna by Governor Keshari Nath Tripathi.
Nitish, who was invited to form a new government by the Governor after Jitan Ram Manjhi's resignation ahead of the trust vote on Friday, has been asked to prove his majority in the Bihar Assembly by March 16.
The senior JD (U) leader had earlier on Friday described his decision to quit office last year as 'a mistake'.
"With folded hands, I apologise to the people of Bihar. Never again will I take such a step. I am ready to lead from the front," he said.
Nitish had stepped down as the chief minister on May 17 last year after his party fared poorly in the 2014 Lok Sabha elections, winning just two seats.
Manjhi, who was chosen to replace him, was asked to step aside to allow the return of his former boss as the chief minister as the party campaigns for the Bihar election due later this year.
Manjhi, however, did not oblige and was expelled by the party. Manjhi later sought a trust vote but quit abruptly when it was clear that he would not win.
