Prince Charles' Clarence House office said the heir to the throne is "delighted to announce the engagement of Prince William to Miss Catherine Middleton."
The couple got engaged last month during a vacation in Kenya.
They are due to marry next spring or summer in London, Clarence House said.
The couple are both 28 and met more than eight years ago while both were students at the University of St. Andrews in Scotland.
"Prince William has informed the queen and other close members of his family," the statement said.
"Prince William has also sought the permission of Miss Middleton's father.
"Following the marriage, the couple will live in north Wales, where Prince William will continue to serve with the Royal Air Force."
William, second in line to the throne, is an RAF search and rescue pilot.