Theresa May has delivered a farewell speech in Downing Street before tendering her resignation to the Queen.
She wished new Prime Minister Boris Johnson and his government well, adding: “Their successes will be our country’s successes.”
Earlier, Mrs May faced MPs’ questions for the final time and looked visibly emotional as she left to applause.
Mr Johnson will speak outside No 10 too, before announcing several senior cabinet appointments.
He is expected to use the opportunity to increase the number of women in full cabinet positions and boost the representation of ethnic minorities.
During his journey to Buckingham Palace to accept the Queen’s invitation to form a government, Mr Johnson’s car was briefly held up by protesters from Greenpeace, who formed a human chain across The Mall.
Mrs May gave her final speech in Downing Street – her husband Philip alongside her – before heading to Buckingham Palace.
She said serving as prime minister had been “the greatest honour” and thanked all those who had worked with her.
“This is a country of aspiration and opportunity, and I hope that every young girl who has seen a woman prime minister now knows there are no limits to what she can achieve.”
She said she was happy to hand over to a successor committed to delivering Brexit and creating “a bright future for this country”.