David Cameron will resign on 13 July and Britain will get its first female prime minister since Margaret Thatcher, in the form of British Home Secretary Theresa May.
After failing to convince UK to remain in the European Union in a shocking referendum, Cameron had announced in June that he would step down by October.
May's only remaining rival to replace Cameron - Energy Minister Andrea Leadsom - pulled out of the race following controversy over comments she made about motherhood and leadership.
"Obviously, with these changes, we now don't need to have a prolonged period of transition. And so tomorrow I will chair my last Cabinet meeting. On Wednesday, I will attend the House of Commons for Prime Minister's questions. And then after that I expect to go to the palace and offer my resignation. So we will have a new prime minister in that building behind me by Wednesday evening," Cameron told reporters outside 10 Downing Street on Monday.
May, who actually supported Britain remaining in the EU, reiterated her commitment to Brexit on Monday.
"Brexit means Brexit, and we're going to make a success of it. There will be no attempts to remain inside the EU. No attempts to rejoin it by the back door. No second referendum. The country voted to leave the European Union, and as prime minister, I will make sure we leave the European Union," she said.