Mr Bommai was elected leader of BJP legislature party at a meeting which was attended by Arun Singh, who is incharge of BJP's Karnataka unit and the party's central observers Dharmendra Pradhan and G Kishan Reddy.
According to party sources, only Bommai's name was proposed at the meeting which was also attended by the outgoing chief minister Yediyurappa and the state BJP president, Nalin Kumar Kateel.
The process of electing a new leader lasted for only a few minutes, the sources added.Bommai would be sworn-in as chief minister of the state at 10 am on Wednesday at Raj Bhavan, the sources added.
Bommai is considered as a close-confidant of the outgoing chief minister Yediyurappa, and had served as minister, handling various portfolios including Home, Cooperation, Water Resources and Law and Parliamentary affairs.