Prime Minister Narendra Modi picked Hindu hardliner Yogi Adityanath, who has been accused of inciting violence against India's Muslim minority, to lead its most populous state after his party won a landslide victory last week.
Adityanath's appointment to lead Uttar Pradesh was denounced by opposition party members.
But officials of Modi's Bharatiya Janata Party said Adityanath, who will take charge on Sunday, was the appropriate leader for the state.
"This is a watershed moment in the history of BJP," Venkaiah Naidu, Federal Information & Broadcasting Minister told reporters after BJP officials met in Uttar Pradesh's capital Lucknow on Saturday.
"The mandate is for development, good governance and against caste politics."
Modi's BJP won control of the state a week ago, earning the biggest majority there for any party since 1977, after the Prime Minister pitched himself as a man on the side of the poor.
The win has raised the prospect of Modi's re-election in general elections in 2019.
But Manish Tewari, senior leader at the Congress party, tweeted that Adityanath's appointment was a "harbinger to greater polarisation."
Adityanath, 44, is the head priest of the Gorakhnath Mutt, a Hindu temple in eastern Uttar Pradesh, and a fifth-time lawmaker in the Indian parliament.
He has supported strong laws for cow protection, and also said minority groups that oppose yoga should either leave the country or drown themselves in the sea.
He has also been accused of making inflammatory speeches during the campaign in Uttar Pradesh, where Modi's party didn't field a single candidate from the minority Muslim population.
Professor Sudha Pai, an expert on Uttar Pradesh politics at the Jawaharlal Nehru University, said Adityanath "is not a good choice and will not help Modi's development agenda."
Federal Interior minister Rajnath Singh, telecom minister Manoj Sinha and BJP state president Keshav Prasad Maurya had also been seen as contenders for the post of chief minister.
