While appearing on The Ellen DeGeneres Show Wednesday, the Oscar-winning actress said, "I think it's sublime."
And while she has yet to meet Clooney's fiancée, Amal Alamuddin, Roberts remarked, "She is beautiful and smart, and he is happy and that's what matters to me."
Meanwhile, Clooney turned 53 on Tuesday with his bride-to-be by his side.
The pretty pair jetted off to Cabo San Lucas in advance of the wedding of the actor's close pals Thom Mathews and Karla Jensen.
Last month, Clooney popped the question to Alamuddin and presented the human rights lawyer with a stunning seven-carat diamond ring—reportedly over a home-cooked meal—after just seven months of dating.
While the couple has yet to open up about their engagement, the brunette beauty has already won over Clooney's family.
"We are very pleased," Clooney's father, veteran broadcaster Nick Clooney, told E! News. "We like Amal and we are very excited for our family and thrilled for them."
He added, "They are both wonderful people and hope they have a terrific life ahead of them."