Patnaik was administered the oath of office and secrecy by Governor Ganeshi Lal in a grand ceremony at the Idco Exhibition Ground.
The BJD, which won 112 seats in the 147-member Assembly in the recently concluded elections, held simultaneously with the Lok Sabha polls, has been in power in Odisha since 2000.
It is the first time Patnaik has taken oath in an open public ground. In 2000, 2004, 2009 and 2014, he was sworn in at the Raj Bhavan.
Apart from chief minister’s elder brother and businessman Prem Patnaik, sister and noted writer Gita Mehta, around 7,000 dignitaries including captains of industries attended the swearing-in ceremony.
A large number of BJD supporters and women grass root leaders attended the function.