Firebrand Hindutva leader Yogi Adityanath was sworn in on Sunday as the Chief Minister of a Bharatiya Janata Party (BJP) government in Uttar Pradesh.

Cheered by tens of thousands of supporters at the Smriti Upvan, the 21st Chief Minister of the country's most populous state was administered the oath of office and secrecy by Governor Ram Naik.

Phoolpur MP Keshav Prasad Maurya and Lucknow Mayor Dinesh Sharma were then sworn in as Deputy Chief Ministers -- in that order.

Twenty-two other cabinet ministers were sworn in. Among the ministers of state was Mohsin Raza, a BJP spokesperson and a former cricket player.

Watching the ceremony were Prime Minister Narendra Modi, BJP President Amit Shah, BJP veterans L.K. Advani and Murli Manohar Joshi and union Home Minister Rajnath Singh, a Lucknow MP.

Dressed in his characteristic saffron robes, Adityanath, after taking oath, walked over to and sought the blessings of Advani, Joshi as well as Rajnath Singh.

Outgoing Chief Minister Akhilesh Yadav was present on the occasion and, before the event began, mingled freely with BJP leaders.

The BJP swept to power in the Uttar Pradesh assembly election, decimating the opposition and winning 312 of the 403 seats. Another 13 seats were won by allies.

It marked the return of the BJP to power in Uttar Pradesh after 14 long years.

Among the cabinet ministers are BJP leaders Surya Pratap Sahi, Suresh Khanna, Satish Mahana, Rajesh Agarwal, Dharampal Singh, S.P. Singh Baghel and Ramapati Shastri.

Defectors from other parties who won on BJP ticket were also accommodated: Swamy Prasad Maurya, Rita Bahuguna Joshi, Dara Singh Chauhan, Brajesh Pathak and Nand Gopal Nandi.

Meanwhile, BJP leader and central cabinet minister M. Venkaiah Naidu said that Yogi Adityanath, a Gorakhpur MP, would lead Uttar Pradesh on the development path.

"I am confident Yogiji will soon become the face of development in Uttar Pradesh. He has been a fighter for people's cause. He has declared 'Lok Kalyan Sankalp Patra' of the BJP manifesto is his agenda," Naidu wrote on Facebook.

"Unfortunate that some opponents, communalists are trying to portray him as a rubble-rouser and fringe personality. They should go through his parliamentary debates. Those reveal his seasoned thinking on various issues of governance," Naidu said.

Describing Yogi Adityanath as a politician committed to help the downtrodden, Naidu said it was "unfair" to attribute caste to him. "People of all communities are celebrating his appointment."

Referring to criminal charges against Yogi Adityanath, including attempt to murder and rioting, Naidu claimed the cases were political.