Mandy Moore Channels Kate Middleton in Sheer Red Dress, Jokes She Takes Credit for Choreographing 'La La Land'

The 'This Is Us' star reveals she doesn't mind being mistaken for the film's real choreographer, who shares her name.

Mandy Moore stole the show at the 19th Costume Designers Guild Awards!

While the night celebrated the best in TV, film and short-form costume design, the This Is Us star, who hosted the star-studded fête at the Beverly Hilton Hotel in Los Angeles on Tuesday, turned heads on the red carpet in a stunning floor-length dress that gave us major Kate Middleton vibes.

WATCH: Mandy Moore Completely Slays in a Super Sexy Black Dress at Artios Awards

Rocking a punchy pink pout and a perfectly styled updo with a middle part, Moore donned a sheer red gown by one of the Duchess of Cambridge's favorite dress designers, Jenny Packham.

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She completed her chic look with Stuart Weitzman heels, a red Edie Parker box clutch, and Irene Neuwirth jewelry.

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"On my way to host #cdgas," Moore captioned a photo of her look via Instagram. "Red-y to go ?."

RELATED: Costume Designers Guild Awards 2017: The Complete Winner's List!

And the 32-year-old actress continued to glow as she took the stage to deliver her opening speech. One of the highlights was when she joked about being mistaken for choreographing La La Land, as she shares the same first and last name as the film's choreographer.

"Hosting tonight's show is actually one of the highlights of my year," she gushed. "Another is the warm reception our show, This Is Us, has gotten all across the country. And third is everyone thinking that I choreographed La La Land."

"And I can't really bring myself to correct them," she continued. "So I just smile and I say, 'Thank you so much. I'm so glad you liked the movie.'"

ET's Cameron Mathison caught up with Mandy Moore (the choreographer) earlier this month, where she spoke out on the common mistake, which she says "has been going on for 15 years."

"This is hysterical to me that it's now become like a thing because it's been a thing in my life for a long time," she explained. "Every time I check into a hotel, anything I pay with a credit card it's like, 'Oh, we thought you were the other one.'"

WATCH: 'La La Land' Choreographer Mandy Moore Details Ryan Gosling & Emma Stone's Giggle-Filled Rehearsals

"So my twitter handle is @nopenother because the amount of times I had to say that in my life," she added. "But she -- what's so crazy was, at the Golden Globes, Emma [Stone] and Damien [Chazelle] had thanked me, which was so kind, in their acceptance speeches, and then the next girl to come out and present was Mandy Moore. I'm like of all actresses in the entire industry, I was like, 'This is amazing!' I was laughing so hard, I thought It was so cool."

Hear more from her exclusive interview with ET in the video below!