The 29-year-old actress is engaged to French journalist Romain Dauriac and the couple are currently expecting their first child together.
And she was clearly proud of her changing shape as she beamed posing for photographers at the premiere of Captain America: The World Solider in Los Angeles last night.
Wearing an intricate lace and impossibly feminine monochrome dress, she proudly showed off her teeny tiny baby bump.
The expectant mum, who was previously married to actor Ryan Reynolds for two years, says she lacks the skills to organise her upcoming nuptials to Dauriac.
“Oh, I don’t plan anything. I’m terrible at planning,” she told Access Hollywood.
“Yeah, I’m not gonna plan anything – I like to wing it!”
Scarlett has other things to think about currently, as her professional life is booming.
Recently she has been following a vegan diet to get into shape for her role as Black Widow in upcoming feature The Avengers: Age of Ultron, and she confesses eating this healthy was dull beyond belief.
“All boring!” Scarlett lamented about her food and fitness regimen.
“Boring 5 AM workouts. Salad and chicken and, you know, nothing else, pretty much. It’s that old tried and true ‘work out like a dude and eat like a rabbit’ [plan],” she laughed.
Scarlett and her fiancé Romain went public with their romance in November 2012. They got engaged in September 2013, after he proposed with a gorgeous vintage Art Deco ring.
This will be Scarlett’s second marriage, as she was previously wed to actor Ryan Reynolds, from 2008 to 2011.
The Avengers: Age of Ultron, which also stars Chris Hemsworth, Robert Downey Jr., Elizabeth Olsen and Jeremy Renner, is currently filming and will reach theatres in 2015.