He slammed the Congress-JDS alliance as "unholy" and charged they were out to grab power though the people had "rejected them outright".
"I am sure of winning the vote of confidence and my government completing five years," said Yeddyurappa, who has been given 15-days window by Governor Vajubhai Vala in a controversial decision that has been challenged in the Supreme Court.
He was addressing his first press conference soon after taking the oath following an overnight legal battle in the Supreme Court where the Congress-JDS combine made a desperate push to stall the government formation.
Yeddyurappa also appealed to the legislators to vote according to their "conscience" and uphold the people's mandate.
"I am 100 per cent sure of the success," he said, striking a confident note on emerging victorious in the trial of strength in the assembly.
"I have people's support for me and my party," said Yeddyurappa, who has now a tough task to muster the numbers to reach the half mark of 112.
The BJP has emerged as the single largest party with 104 seats in the May 12 elections which threw up a hung assembly.