The A-list couple have been dating for eight months and according to the New York Daily News the 38-year-old actress was seen wearing a ring on her left hand as she arrived at LAX on Wednesday.
Charlize and Sean, 53, are completely loved up (they were all eyes for each other at the Christian Dior show during Paris Couture Week last month) and Us Weekly has reported they're set to tie the knot in South Africa this summer.
The two are currently working together on set of The Last Face which Sean is directing and Charlize is starring in, but they've actually been rubbing shoulders in the industry for the last 18 years.
"They want to get married very soon" a source told Us Weekly.
"Charlize has seen Sean grow up, he's a wiser soul and much more patient. They're looking to the future with a lot of hope."
A stunning South African ceremony with their nearest and dearest (think low-key but completely luxe) - we can definitely see that happening.
As for the exact engagement plans, we'll keep you posted.
LOVE CHARLIZE'S STYLE? Wait to until you see these looks from the actress, producer, director, and fashion model. And yes she has the most perfect pins that ever were.
MORE! Catch up on all the latest on Charlize Theron right here.