The Hollywood actress took inspiration from wartime fashion in a floral cap-sleeve blouse with a necktie, a terracotta pencil skirt and nude peep-toe heels.
And of course the Lost In Translation star, who is currently sporting strawberry blonde tresses, was wearing lashings of the brand's new red lipstick which she described as capturing 'old Hollywood glamour'.
Demure: Scarlett Johansson wore a pencil skirt and blouse from Dolce & Gabbana's Spring Summer 2009 collection the brand's make-up launch at London's Selfridges today
The usually buxom 24-year-old looked lean and petite as she posed for the cameras having recently slimmed down to fit into a skintight catsuit for her Iron Man 2.
She transformed her figure to play Russian spy Black Widow alongside an all-star cast that included Robert Downey Jr, Mickey Rourke, Samuel L. Jackson and Gwyneth Paltrow.
Lip service: The actress wore lashings of the label's red lipstick on her
But she insists the results were worth it: 'I kicked some major butt.'
The film's director Jon Favreau added: 'She was wearing an unforgiving costume.' She didn't eat much, that's for sure. She likes food, as do I, and she was definitely on a low-carb diet and training very hard. It was amazing.'
While her career is on track, there have been reports her romantic life isn't running quite so smoothly.
Lean times: Scarlett recently lost weight to wear a skintight catsuit for Iron Man 2
Ready for her close up: Fans try to catch a frame for the Hollywood star
The rumours began when Reynolds didn't turn up to promote new film adaptation of The Green Lantern, despite his wife attending for Iron Man 2.
But his spokesperson insists the couple aren't having marital problems, saying: "[It] is completely untrue. Warner Brothers never planned to have Green Lantern as part of their panel at this year's Comic-Con and Ryan is in Europe shooting a film.'
A friend added: 'Any reports of a fight are ridiculous.'
All made up: Scarlett emulates Marilyn Monroe in this advert for Dolce & Gabbana