The hunk was given the title in 2008 following his work to raise awareness about the violence in Darfur, Sudan, and during his six years in the role he was able to travel to the Democratic Republic of Congo and South Sudan.
In March 2012, George was arrested, but shortly released, in a protest over the crisis in Sudan, and he also got the chance to meet with President Barack Obama to discuss his concerns about the country.
The news comes after George's parents Nick and Nina confirmed yesterday that he had popped the question to Amal, 36, and they are "thrilled" that he is to tie the knot with a "wonderful young woman".
George was previously married to actress Talia Balsam from 1989 until 1993 and has had a number of high-profile relationships since.
- Bang! Showbiz