The 52-year-old actress joins the "John Wick" franchise as Sofia, an assassin and a close friend of Keanu Reeves' title character, who is still on the run after killing Santino D'Antonio in the Continental in "John Wick: Chapter 2".
While she has credited training for the film for getting her in the "best shape" of her life, doing so didn't come without its pitfalls.
"I broke three ribs when I was rehearsing for John Wick," she admitted during an interview with U.S. TV show "Extra". "It's like a badge of honour for me, we don't know how it happened. I worked for a little while with broken ribs until I could no longer do it."
As for the training involved in preparing for the movie, Halle had to take on "hours and hours of stunt training", as well as "gun training, dog training and strength training."
She also had to watch what she ate in order to get her figure as lean and athletic as possible.
Working with Keanu in the movie was also a somewhat daunting prospect for Halle, who explained: "It was pretty amazing. It was a little terrifying at first because he's so damn good, and I wanted to be on the same level as him. I didn't want to disappoint him."
Despite Halle's fears, she needn't have worried, as director Chad Stahelski promised her character "isn't going anywhere" when asked about the actress reprising the role for a fourth instalment in the franchise.
The new "John Wick" sequel opens in cinemas next month (May 2019).