Phagu Chauhan was on Monday sworn in as the 40th Governor of Bihar, an official said.
The 71-year-old Phagu Chauhan succeeded Lalji Tandon, who is now the Governor of Madhya Pradesh.
He was administered the oath by Patna High Court Chief Justice Amreshwar Pratap Sahi at a programme held at Raj Bhawan here in the presence of Chief Minister Nitish Kumar and deputy chief minister Sushil Kumar Modi, besides several ministers.
Phagu Chauhan, a six-time MLA from Ghosi Assembly constituency in Uttar Pradesh's Mau district, had resigned from the UP Assembly on Friday.
After having won the Assembly election for the first time in 1985 on a Dalit Mazdoor Kisan Party (DMKP) symbol, he was returned as an MLA again in 1991 on a Janata Dal ticket.
He won the seat in 1996 and 2002 on the BJP symbol. Phagu Chauhan again won Ghosi in May 2007 on a BSP ticket but later returned to the saffron party and won the Assembly election for the sixth time in March 2017.