The stunning, floor-length gown showed off the results of Kelly's latest fitness regime.
Kelly, 35, recently said on Twitter: "Lost 3inches around my waist but keeping the kurves."
The star shared a number of snaps from her night out at Entertainment Weekly's celebration honouring the 2015 SAG Award nominees.
Her fab figure took centre stage at the glamorous bash at LA's Chateau Marmont.
Kelly's been following a low carb, low sugar diet of late and has been keeping fans updated with what she eats.
We're pleased to report that she's making sure she eats yummy food and we love the sound of the shepherds pie with cauliflower mash she munched recently.
She's also allowing herself treats and opts for a low calorie gin and tonic when she's out for drinks.
As well as a healthy approach to her diet, Kelly's been working hard in the gym.
She's shared a couple of jaw-dropping gym selfies and told her Instagram: "Smashed Abs today!! Feeling Stronger everyday #dedicated #Focus #Fitness #24inchWaistin6Weeks #LetsDoIt #curves."
We're impressed, Kelly!
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