Keshav Prasad Maurya (right) was sworn in along with Yogi Adityanath and 51 other ministers.
Yogi Adityanath will have two deputies, like before. Keshav Maurya, who lost the election, has been retained but Dinesh Sharma, who did not contest the election, has been replaced by Brajesh Pathak.
Mr Pathak, a top Brahmin leader, was Law Minister in Yogi Adityanath's first government. A former Lok Sabha MP, he switched to the BJP from Mayawati's BSP in 2017.
The two deputies were among 52 ministers sworn in on Friday along with Yogi Adityanath for his second consecutive term as the Chief Minister of Uttar Pradesh.
The announcement of Mr Maurya and Mr Pathak ended over two weeks of suspense following the elections results on March 10 and a flurry of meetings between the top leadership of the BJP in Delhi and Adityanath.
As speculation compounded over the days-long wait, the BJP rubbished reports that a disagreement over cabinet names had held up the swearing-in. Yogi Adityanath and Prime Minister Narendra Modi are "completely in sync" on cabinet names, sources said two days ago, downplaying any rift.
PM Modi, Defence Minister Rajnath Singh, Union Home Minister Amit Shah and several Union Ministers were present at the grand ceremony in Lucknow's Ekana Stadium. Chief Ministers of the BJP ruled states and party leaders also attended the oath-taking ceremony.
Adityanath was sworn in by Governor Anandiben Patel in a packed with more than 50,000 in attendance.
The monk-turned politician will take the reins of the most populous state for a second time in a row after completing his full five-year term - a feat repeated after 37 years.
During the electoral campaign for the Uttar Pradesh elections, the Prime Minister had praised Yogi Adiyanath's work and his slogan - "UP plus Yogi bahut hai upyogi" (UP plus Yogi is very useful) became quite popular.
In a surprise move after the 2017 Assembly elections, the BJP chose Adityanath as the Chief Minister after winning the elections without a Chief Ministerial nominee.
After becoming the Chief Minister of the state, he kept 36 ministries under his direct control, including Home, Economics and Statistics, Sainik Welfare, Home Guard, Personnel and appointment, as well as Civil Defence.
Before being sworn as UP chief minister in 2017, he was Gorakhpur MP for five consecutive terms from 1998 to 2017.
The BJP won 255 seats in Uttar Pradesh with its allies in the state also registering impressive performance. The chief minister is expected to carry the momentum of the party's electoral victory to fulfill the poll promises and give a further push for the development of the state in his second term.