Badenoch, 44, came out on top in the race with former immigration minister Robert Jenrick, winning 57 percent of the party members' votes.
Badenoch, who became the first black leader of a UK political party, said she was "hugely honoured" to take on the role but that "the task ahead is difficult".
"We have to be honest about the fact that we have made mistakes and we have missed the standards. It's time to get on with the job, it's time to renew ourselves," she said.
The former equalities minister now faces the daunting task of uniting a divided and weakened party that was decisively ousted from power in July after 14 years in power.
Badenoch will become the official leader of the opposition and face Labour's Keir Starmer in the House of Commons every Wednesday for the traditional Prime Minister's Questions.
However, she will lead a significantly reduced group of Tory MPs in the chamber following the party's dismal performance at the election.
It must develop a strategy to regain public trust and at the same time stop the flow of support to the right-wing Reform UK party, led by Nigel Farage.
Having campaigned on a right-wing platform, she also faces the prospect of future difficulties within the Tory ranks, which include many centrists. | BGNES
