Governor Syed Ahmed administered the oath of office and secrecy to Das at the Birsa Munda Football Stadium here.
Nilkanth Singh Munda, Chandreswar Prasad Singh, Louis Marandi (all BJP) and Chandraprakash Choudhary (Ajsu party) were also sworn-in as cabinet ministers.
Jharkhand has a maximum limit of 12 ministers, including the chief minister.
Dense fog in New Delhi led Prime Minister Narendra Modi and BJP President Amit Shah to cancel their visit to Jharkhand to attend the ceremony.
Das became the tenth chief minister after Babulal Marandi (once), Arjun Munda (thrice), Shibu Soren (thrice), Madhu Koda (once) and Hemant Soren (once) of Jharkhand governments in the 14 years of its creation.
After being elected as the BJP’s legislature party leader, Das had staked claim to form government on December 26 at the head of BJP-Asju alliance.
Das joined the BJP as a worker and then gradually rose through the party ranks before getting the first break when he was nominated as party candidate from Jamshedpur (East) in the 1995 Assembly elections.He went on to win the seat five times.
He became a minister for the first time after the creation of Jharkhand in the Babulal Marandi government and got berths in the subsequent two governments led by Arjun Munda before becoming the deputy chief minister in the Shibu Soren-led government in 2009.
He held portfolios of finance, labour and urban development during his stint as cabinet minister.
PTI