"Being engaged is an exciting time to enjoy and to really savour," she added.
The Her star, who was seen wearing her beautiful vintage Art Deco ring at the Venice Film Festival in September, told Good Morning America in January she was in no rush to walk down the aisle.
"I am not doing any wedding planning," she admitted.
Scarlett's art deco engagement ring
Scarlett was previously married to Canadian actor Ryan Reynolds from 2008 until 2011 — he wed Blake Lively in September 2012.
She has previously spoken of her desire to have children. "I would like to have my own family, that would be nice," Scarlett told the Mail in December.
Scarlett has been busy promoting her latest film Her
"They say it's never the right time, and I am sure that's true, but I think you have to plan it like anything else.
"At some point it is something I look forward to.
The couple looked loved up at the Cesar awards
"I am fortunate in that I have had a very long career - 20 years - that has been very diverse," the former child star continued. "So, you know, picking a time to plan a family feels like something that I could do and not feel as though I was missing out."