Ellie, who is currently on tour in the US, was all smiles as she walked down the red carpet on Tuesday night (18 March).
The 'Anything Can Happen' singer didn't just show off her legs though, as the deep v-cut of the dress showed off her cleavage, while the shoulder pads accentuated her frame.
Ellie, who teamed the simple frock with pointed black heels, lends her voice on the Divergent soundtrack. Her three songs, 'Beating Heart', 'Dead in the Water' and 'Hanging On' feature during the action film's most pivotal moments.
Speaking to MTV this week, Ellie said: "I've always loved the idea of doing a film soundtrack, so when I'd seen the film and they put some of my songs to it, my face lit up. I felt very excited.
"It's the first thing I've done where my voice is used amongst the soundtrack rather than just songs," she added.
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Watch Ellie's music video for 'Burn' below: