Governor Syed Ahmed administered the oath to all the six newly-inducted ministers simultaneously at Raj Bhavan.
The newly inducted ministers are Champai Soren, Simon Marandi, Hazi Hussan Ansari, Jaiprakash Bhai Patel (all JMM), Suresh Paswan (RJD) and Geetashree Oraon (Congress).
With Sunday's expansion, chief minister now has nine ministers in his council.
As per the constitutional provision he can have a maximum of 12 ministers including himself.
Hemant Soren-led UPA government (JMM, Congress, RJD and some smaller parties and Independents) had taken oath on July 13 after staking claim for government formation on July 9.