The actress, who plays Anastasia Steele in the movies, was speaking on Jimmy Fallon’s US chatshow last night when she was asked if Fifty Shades Freed really is the final instalment.
“It is the final film,” Johnson confirmed.
She joked: “It’s the last film ever made – of all the films. You’re welcome!”
When Fallon pushed her on rumours that Grey, a new book EL James had penned – retelling the first story through Christian Grey’s perspective – Johnson remained firm that this is the end of the road.
“No, I don’t think so,” she insisted.
Teasing the film’s darker edge, she said: “We’re married; Anastasia and Christian [Jamie Dornan] get married, and it becomes more of a thriller and it’s a lot more intense.
“There are people that wanna get to them and maybe kill them. It’s crazy.”
On returning to work with the likes of Dornan, she beamed: “It was just so nice to do it again.
“It gets really crazy. Anastasia has evolved into a tough young woman and it’s awesome.”
Dornan, meanwhile, hinted in a recent interview that he still “can’t believe” the movies were even made.
Fifty Shades Freed is out on February 9.