The actress looks stunning and oh-so-youthful in the picture, with her trademark blonde hair replaced with a gorgeous chestnut shade.
Her usual centre parting has been pushed to the side, with shorter layers framing her face.
Cute freckles across her nose lend a youthful look to her face.
Sam, who left EastEnders at the very start of 2017, when her character Ronnie Mitchell drown alongside sister Roxy, captioned the picture: "Girl On The Train is darker."
Fans rushed to praise the new look.
One wrote on Twitter: "Oh my Lord!!! WOW "
A third posted: "Woah cool look, if someone had shown me that photo I would not have guessed that was you!"
The 43-year-old is taking the title role in the UK theatre tour of popular thriller Girl On The Train, penned by Paul Hawkins. Emily Blunt played the part in the film adaptation.
SAMANTHA WOMACK (@Sam_Womack) will headline the UK Tour of The Girl on the Train from January 2019.
Adapted from Paula Hawkins’ novel – an international phenomenon selling over 20 million copies worldwide – this gripping new play will keep you guessing until the final moment. pic.twitter.com/R8HjRj3r9g
— InterTalent (Actors & Creatives) (@InterActors) 26 July 2018
Earlier this week, Sam revealed she had just completed a shoot for the publicity of the show.
Have just finished my first photo shoot for Girl on the train. In theatres next year 🤪🙏🏻
— Sam Womack (@Sam_Womack) 25 July 2018
This isn't the first time Sam has turned to the dark side... she sported a poker-straight, raven wig last year for her stint in The Addams Family.
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