The 39-year-old Grindhouse actress has been dating Davey since last year.
The star has been pictured wearing a giant sparkler on her wedding ring finger in the past week and her publicist informed E! News that she is indeed "happily engaged".
Rose has committed to wed twice before.
She was engaged to rocker Marilyn Manson, whom she was with for three years, before breaking off the relationship due to "lifestyle differences" in 2001.
Rose then planned to wed Grindhouse director Robert Rodriguez, but the pair also didn't make it down the aisle. The former couple split after spending two years together.
It is unknown when or where Rose and Davey's wedding will take place at this time.
Although Rose has kept mum on her real-life romantic relationships, she has previously shared a secret steamy long-held fantasy.
Apparently Rose, a longtime LGBT advocate, finds women incredibly attractive.
"I'd be stoked to do a lesbian love scene. When asked if I've kissed a girl, I could finally say, 'Why, yes, I have. And I got paid,'" Rose told The Advocate.
"To this day, I only go to gay clubs. I'm perfectly at home there. I also like watching hot boys and hot girls who can dance