The oath of office was administered by President Ram Nath Kovind at the Rashtrapati Bhavan.
Earlier in the day, the nine new ministers met PM Modi and party chief Amit Shah.
Among the new ministers, who took oath, some include ex-Mumbai Police chief and now BJP lawmaker Satya Pal Singh, retired diplomat Hardeep Puri, retired IAS officer KJ Alphons and former Home Secretary RK Singh, also a lawmaker.
They all will be Ministers of State.
The others include BJP lawmaker from Bihar-Ashwini Kumar Choubey and Shiv Pratap Shukla from Uttar Pradesh, Virendra Kumar from Madhya Pradesh, Ananthkumar Hegde from Karnataka and Gajendra Singh Shekhawat from Rajasthan.
The main focus is now on Modi’s decision in selecting the new Defence and Railways ministers.
Power Minister Piyush Goyal could be the new Rail Minister, NDTV reported citing sources.
Seven ministers have resigned from the Modi government since Thursday.
Apart from them, few other ministers had also resigned in 2017 that led to a number of vacancies in Modi’s cabinet.
Manohar Parrikar resigned as the Defence minister to become the Goa chief minister.
Presently, Arun Jaitley is handling the two portfolios, finance and defence ministries.
Rajiv Pratap Rudy and Sanjeev Balyan both said they were told to resign by the party and they unquestioningly did so.
“It’s not my decision, it’s the decision of the party, and I will follow (it),” Rudy told NDTV.
According to media reports, Rudy and Balyan are expected to be given key organisational roles in the BJP in preparation for the 2019 elections.