Mr Jagadish Shettar will be sworn in Chief Minister on Thursday.
Mr Shettar, the Rural Development and Panchayat Raj Minister in the current Cabinet, was elected the leader of the BJP legislature party on Tuesday.
The legislative party meeting was attended by former party president Mr Rajnath Singh, Mr Ananth Kumar, Mr Eshwarappa, Mr Shettar and the Chief Minister, Mr D.V. Sadananda Gowda.
Mr Shettar is a close ally of the former Chief Minister, Mr B.S. Yeddyurappa.
Mr Shettar will be third Chief Minister in the last four years. After Mr Yeddyurappa, who became Chief Minister in 2008, was forced to resign after he was indicted by the State Lokayukta in connection with illegal mining, Mr Gowda became Chief Minister with support of Mr Yeddyurappa, defeating party candidate Mr Shettar in a poll held to choose new legislature party leader in August 2011.