In the upcoming remake, Ejogo plays a singer who develops a drug addiction to cope with her sudden rise to fame.
And because the script so closely mirrored Houston's real life, the I Will Always Love You hitmaker, who portrays Ejogo's onscreen mum, took the 38 year old under her wing to pass along a few tips in a bid to make the film as realistic as possible.
The actress tells the New York Post, "She was very open with me about her battles. I was quite shocked. She shared some very personal stories. She was willing to be totally vulnerable so I could understand what it was like. She wanted my character to be authentic, and she went there in order for me to be able to bring that to the screen."
Even though Houston, who passed away in February (12), will not get a chance to see the finished product, Ejogo insists the film will serve as a cautionary tale for her daughter with ex-husband Bobby Brown, Bobbi Kristina, and all other young girls trying to make it in the business.
She adds, "She was willing to be the example of what to avoid. She made this film for her daughter and for all girls to recognise the importance of not letting your light be dimmed by anything. To have gone through what she'd gone through, the public humiliation, and still have the guts to share that story is incredibly brave."