Prince William will join the Army after gaining a place at the military academy at Sandhurst, Clarence House has said.
Prince William had to perform aptitude tests
He was given a place after tests of his mental, physical and emotional aptitude for becoming an officer.
William, 23, is set to join the college in January, after work experience at HSBC bank. His younger brother Harry, 21, is already training at Sandhurst.
William was "absolutely delighted" at securing a place and Prince Charles "very proud", Clarence House said.
Harry joined Sandhurst in May, four months later than planned to allow him to recover from a knee injury, and is due to finish in April.
The princes will be based in different parts of the academy - William with new recruits in Old College and Harry in New College, where cadets are taught in their second and third terms.
The Prince of Wales congratulated his eldest son. A Clarence House spokesman said Prince Charles was "very proud" and "thrilled" for him.
William took the Regular Commissions Board tests - including an assault course, physical tests, a planning exercise and interviews - with about 20 other candidates over four days.
The annual pass rate of the tests is 60%.
Prince William said: "I am absolutely delighted to have got over the first hurdle, but I am only too well aware, having spoken so much to Harry, that this is just the beginning.
"I am really looking forward to taking my place alongside all the other cadets at Sandhurst."
Before then, William will spend three weeks shadowing HSBC staff, mostly in the charity services division.
The prince has recently undertaken land management experience on a country estate, and is also set to spend time with a mountain rescue team.
Most of the 800 recruits accepted at Sandhurst each year are graduates like William, who left St Andrews university in the summer with a 2:1.
Sandhurst has intakes each year in January, May and September.
William will endure a tough breaking-in period and will be totally immersed in Army life in the first five weeks of the 44-week course.
Recruits rise at dawn, finish late, are not allowed off-site and have very little free time.