Dressing aptly for the occasion, Stacey channeled her inner princess with her girly getup as she rubbed shoulders with the movie's leading stars Lily James, Richard Madden and Helena Bonham Carter.
The 25-year-old teamed a cute embellished crop top - featuring a jewelled hem and neckline - with a floaty full circle grey skirt and slip-on sandals.
Letting her outfit take centre stage the mum-of-two swept her long blonde locks up into a tousled up-do, leaving a few strands loose to frame her face.
She opted for natural-looking make-up, dolling up her peepers with a subtle smoky eye and perfectly arched brows. To finish her look, Stacey added a slick of nude pink lipstick across her lips.
At the event, the former X Factor star joined the likes of Kimberly Wyatt, Amy Willerton and Michelle Heaton and her husband Hugh Hanley.
Prior to her arrival on the blue carpet, it seems Stacey was more than excited to be heading to Leicester Square to watch the Cinderella movie.
She tweeted: "I shall go to the ball! So excited #CinderellaPremier! Wish my Prince Charming was there, but u can't have it all! X"
Stacey's appearance in London comes as she prepares to make her own cinema debut next week.
Last month, the starlet announced she had landed herself a role in the UK version of The Spongebob Movie: Sponge Out Of Water, providing the voice for one of the characters in the animated film.
Other stars that will feature in the film include TV personality Alan Carr and YouTube's Joe Sugg and Caspar Lee.
As well as her movie role, Stacey has also revealed she will finally be releasing her debut album - six years after she appeared on The X Factor.
Her album titled Shy will feature her new single of the same name that she co-wrote with Rita Ora.
Speaking about her new release, Stacey said: "Making this album the best it can be has been hard work but so rewarding. I can't wait for people to hear it. I'm so proud of it!"
We can't wait to hear it!
Stacey's debut album Shy is set to be released in April.
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