To kick things off and stir her fans into a a frenzy, EL James posted a picture of the on-set clapper board with the caption, "Action!"
The cast are currently filming their first scenes in Vancouver, Canada (conveniently this is where the Fifty Shades of Grey 'parent' story Twilight was also filmed. Coincidence? We think not.).
Despite the smattering of cynical 'why is the world subjecting us to this'-style Tweets, the rest of the Twittersphere seems pretty darn happy that the movie is now under way.
But considering the film doesn't hit cinemas until February 2015, we're sure there's more Fifty Shades hysteria to come.
A whole year of this. We're not sure we've got the stamina.
Take a look at some of the more excitable fan reactions...
The filming for Fifty Shades has officially started!— Gyrating Ginger (@Raina_Is_Me) December 1, 2013
It's officially December. it's like fifty shades month to me cause the filming and the rereading and all the news. :")— aisha. (@steelesessed) November 30, 2013
Are you a Fifty Shades of Grey superfan? Tweet us @handbagcom
HAVE SEX LIKE FIFTY SHADES OF GREY TONIGHT
IS DINOSAUR PORN THE NEW FIFTY SHADES OF GREY?
MORE SEX NEWS