Yogi Adityanath took the oath of office in the Uttar Pradesh state capital of Lucknow at an open-air ceremony attended by Prime Minister Narendra Modi and other leaders of India's ruling party.
Adityanath is a five-time member of parliament who has offended many in the country with his polarizing statements attacking the Muslim community.
His rhetoric has raised concerns among Uttar Pradesh's Muslims, who form nearly a fifth of the state's population. With a population of 220 million, Uttar Pradesh would be the world's fifth-most populous if it were a country.
Adityanath tried to reassure Uttar Pradesh citizens that his top priorities were good governance and development of the state, among the poorest in India.
Modi's Bharatiya Janata Party (BJP) fielded no candidates from the Muslim minority that makes up 19 percent of the population in the state.
A spokesman for the BJP, however, claimed the government did not make any distinction between citizens on the basis of religion.
One of India's most prominent Muslim politicians, former Jammu and Kashmir state chief minister Omar Abdullah, said in a tweet that Muslims in Uttar Pradesh "must be terrified of what the future has in store for them."
India's 1.3 billion people are about 80 percent Hindu and 14 percent Muslim, with the rest made up of Christians, Sikhs and other minorities.
It is officially a secular nation, but the BJP has for years fought elections on a Hindu nationalist agenda, with party members in the past being accused of making anti-Muslim statements to polarize Hindu voters.