Watch the Royal couple talking about their engagement
Prince William is second in line to the throne.
The couple met at St Andrews university in Scotland, nine years ago.
The prince asked Kate's dad for permission to marry his daughter and the Queen has also given the couple her blessing, saying she's "absolutely delighted" for the pair.
After the couple are married, they will live in north Wales while the prince continues working as a helicopter pilot with RAF search and rescue for the next three years.
Prince William has given Kate Middleton his mother's engagement ring
Prince William and Kate Middleton met while studying on the same history of art course at St Andrews in 2001, although William later switched to study geography.
For several years, they shared accommodation with friends and Kate has been credited with persuading the prince to stay on as he struggled to adjust to university life during his first year.
After dating for several years, the pair split up for a couple of months in 2007, but soon got back together leading to countless rumours about their possible engagement. until Tuesday's official announcement.