42-year-old Cam was at the the Academy of Motion Picture Arts and Sciences' Hollywood Costume Luncheon on Wednesday looking super glam in a black Isabel Marant dress paired with Givenchy shoes when she flashed said ring.
The lady was all smiles as she swept her hair from her face revealing the diamond ring bling (a gold figure-eight design with diamond detailing and a diamond band).
She wasn't shy about flaunting the ring during the photocall for the event, and she wore it all evening wining and dining with Benji.
Cameron has been dating the 35-year-old Good Charlotte guitarist since April. The couple are clearly smitten and while the relationship is still fairly new, we love the idea of them being engaged.
As for Cameron and Benji having kids? This isn't on their agenda.
"It's so much more work to have children. To have lives besides your own that you are responsible for, I didn't take that on. That did make things easier for me," Cameron told Esquire magazine.
"A baby, that's all day, every day for eighteen years. Not having a baby might really make things easier, but that doesn't make it an easy decision.
"I like protecting people, but I was never drawn to being a mother. I have it much easier than any of them. That's just what it is. Doesn't mean life isn't sometimes hard.
"I'm just what I am. I work on what I am. Right now, I think, things are good for me. I've done a lot. And I don't care anymore" she added.
LOVE CAMERON'S STYLE? Take a look through her style evolution to see all her greatest sartorial moments.