The actress, 28, reprises the role of Anastasia Steele for the final time in the movie, which lands next week.
However, speaking to Seth Meyers on his US chatshow this week, she revealed why the notorious X-rated sequences were especially “tricky”.
It’s no secret that the film was shot back-to-back with its predecessor Fifty Shades Darker, but what that meant was that lots of similar scenes had to be shot in one bulk, so as to make the use of specific locations.
This, it seems, meant that Johnson and co-star Jamie Dornan had to shoot a huge number of their X-rated moments in quick succession.
“It was tricky because we had to go back and forth [between movies],” she recalled.
“Some of the locations would be the same – we had to do all of the sex scenes at the same time.
“We did them all back-to-back, pretty much, because they’re in the same locations.
“And so you want to try and mix it up and not have them all be the same!”
What’s more, Dornan revealed earlier this week that Freed could actually have more steamy scenes than ever before.
“The third one feels like a different genre. There’s still sex in it! We’ve kept a fair amount,” he told Ellen DeGeneres.
“Someone was telling me there’s more sex in the third one than any of the other two. But I don’t sit there with a timer.”
Fifty Shades Freed is out on February 9.