Nayab Singh Saini was sworn in as the Chief Minister of Haryana hours after the surprise resignation of Manohar Lal Khattar from the post along with his Cabinet ministers.
Five others took the oath as members of the new council of ministers along with Saini.
They are BJP leaders Kanwar Pal, Mool Chand Sharma, Jai Parkash Dalal and Banwari Lal and Independent MLA Ranjit Singh Chautala.
Saini was administered the oath by Haryana Governor Bandaru Dattatreya during a ceremony held at the Raj Bhavan here.
He bowed before Khattar and sought his blessings after being sworn in.
Earlier in the day, the BJP named OBC leader Saini (54) as Haryana's new chief minister.
The selection of Nayab Saini, an Other Backward Classes leader - also represents the BJP's focus on caste and OBC equations in each state before an election.
He is the party's state unit president and the MP from Kurukshetra.
The development comes just weeks ahead of the Lok Sabha elections.
Khattar's second term as chief minister was also to end in October when the assembly polls are due.
Khattar and all 13 other members of the BJP-led council of ministers submitted their resignations to the governor as a team of the party's central observers arrived in Chandigarh.