Oscar winner George and British-based lawyer Amal Alamuddin became engaged in April 2014 after reportedly dating since the previous October.
Chatting on Ellen DeGeneres' Show, his close friend Julia said: "I think it's sublime. She is beautiful and smart and he is happy and that's what matters to me."
Julia and George have been friends for a long time – in fact, earlier this year Julia and another close friend of George's, Sandra Bullock, publicly joked about sharing custody of him.
Sandra quipped in January: "Apparently Julia, you and I are in a dispute over George Clooney. We talked about this, right? It's shared custody and we're both fine with it..."
George's proposal to Amal had surprised many as he'd always been seen as the ultimate Hollywood bachelor thanks to his previous relationships with beautiful celebrities that never ended in marriage.
While George and Amal have yet to publicly comment on their marriage plans, members of their family – and colleagues – have been open at voicing support.
George's broadcaster dad Nick has described Amal as a "wonderful young woman" and said he's thrilled for her to join their family.
Amal's law firm, meanwhile, issued a statement saying: "She brings a bright light to everything she is involved in, and I am so delighted at her happy news."
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Watch Julia chatting about George's engagement below:
Stars who became engaged in 2014 in pictures:
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