"It was a whole James Bond situation," the actress tells U.S. talk show host Ellen DeGeneres. "It was surprising... He's very charming and very thoughtful and romantic. But yeah, I was surprised.
"Even if you kind of imagine what that moment's gonna be like, it's still a beautiful moment. I think, more than anything, when someone tells you they want to spend their life with you, that's a lovely, special thing".
It's the third time that has happened to Scarlett, who was previously married to Ryan Reynolds and French journalist Romain Dauriac, the father of her five-year-old daughter, Rose.
Jost popped the question back in May after dating the movie star for two years.