The couple announced their engagement last month. The queen said she was "absolutely delighted" for the couple, Buckingham Palace said hours after the announcement.
Like the queen, Middletons' parents, Michael and Carole Middleton, said after the announcement they too were "absolutely delighted."
"The Prince of Wales is delighted to announce the engagement of Prince William to Miss Catherine Middleton," a statement from Clarence House read.
Prince William, 28, asked Middleton, also 28, to marry him while the two were on vacation in Kenya last month, the statement said.
The happy couple appeared for the first time for reporters arm-in-arm before a barrage of camera flashes, Middleton wearing the famous engagement ring worn by Princess Diana.
"He's a true romantic and we had a wonderful holiday in Africa and it was out there in a very quiet lodge and it was very romantic and it was very personal time for both of us," Middleton said.
In an interview with Britain's ITV News' Tom Bradby, Middleton said the proposal came as a surprise, despite years of public speculation that the couple would wed.
"We were out there with friends, so I really didn't expect it at all," Middleton said. "It was a total shock when it came. Very excited."
The announcement came to the elation of Britons, many of whom viewed the engagement as a seemingly inevitable yet unreachable moment.
"It's about time! Congrats," one commenter wrote, a sentiment echoed by hundreds of others.
ABC News' Nick Watt, Sarah Netter, Jason Volack, Bradley Blackburn and Lee Ferran contributed to this report.