Governor Tathagata Roy administered the oath of office and secrecy to Deb at a function at the sprawling Assam Rifles ground which was attended by Prime Minister Narendra Modi and BJP president Amit Shah.
Jishnu Deb Burman of the BJP was sworn in as the deputy chief minister. Deb Burman is yet to be elected as an MLA as polling in his Charilam (Scheduled Tribe) constituency was postponed due to the death of the CPI(M) candidate. The election to the seat is scheduled to be held on March 12.
Seven other ministers, five from the BJP and two from the Indigenous People's Front of Tripura(IPFT), a BJP ally, including its chief N C Debburman also took oath as ministers.
Ratan Lal Nath, Sudip Roy Nurman, Pranajit Singha Roy, Manoj Kanti Deb and the lone woman in the government Santana Chakma are from the saffron party.
Chief ministers of BJP-ruled states - Vijay Rupani (Gujarat), Shivraj Singh Chouhan (Madhya Pradesh), Sarbananda Sonowal (Assam) and Raghubar Das (Jharkhand) were among others who attended the function.
Giant posters bearing images of Modi and Shah dominated the landscape in Agartala.
From the airport to the venue, BJP flags lined up both sides of the street, as party workers wearing saffron colour clothes celebrated in the streets. Security was heightened in the capital city as the prime minister and many other dignitaries attended the ceremony.
"A 100-ft-long stage was erected for the big function. This is a big day for us as it marks a political transition for the state. The victory has been made possible by the development work of Modiji that has inspired our workers in Tripura to work for a change," BJP general secretary Ram Madhav told PTI here.
The alliance had won the Assembly elections with a two-thirds majority in the 60-member House. The BJP had bagged 35 seats and the IPFT eight of the 59 seats that went to polls.
Deb, a long-time RSS volunteer, has been largely credited with the BJP's turnaround in the state.