03/14/2011 at 01:00 AM EDT
When Mandy Moore
learned she'd be walking her first Academy Awards red carpet-and performing at the ceremony too-she knew it was time to call in the big guns. The singer-actress, 26, known for rocking consistently stylish but low-key ensembles, called on designer Monique Lhuillier, whose blue confection she'd just worn to the Golden Globes. "I wasn't one of those women who ever had a fairy-tale fantasy dress," says the Tangled
star (who wore a tea-length frock and flat sandals at her 2009 wedding to singer Ryan Adams). "Now I understand how women get wrapped up in the whole thing!"
Moore's red carpet look came together almost as soon as she slipped into a silk nude mermaid dress. "It was the first one I tried," says Moore. "I was like, 'Okay, I'm done.' " After minor alterations, the floaty tulle and intricate beading (see box) made Moore "look like she'd just rolled around in gems and fairy dust," says Meritt Elliott, who, along with Emily Current, has been styling the star for years. Adds Current: "It was absolutely flawless."
For her performance of Tangled
's Best Original Song nominee "I See the Light," Moore wanted a showstopper that wasn't a Disney costume. So Lhuillier incorporated elements of three dresses Moore loved (the cobalt-blue color, the full skirt and the corseted top)-et voila: "It's that quintessential big, full dress," says Moore. "It almost feels like a big cupcake-but in the best way possible!"
Among Lhuillier's goals: to show off the svelter-than-ever frame Moore (who loves hiking and Pilates) attributes to the balance brought by happiness at home with Adams, their two dogs and two cats. Says Lhuillier: "We wanted to show off her small waist and her shoulders. She has such a feminine silhouette."
In the end, says Moore, her first date with Oscar was the stuff of true Cinderella fantasy. "I just really took it all in and enjoyed it as much as I possibly could," she says. "It was a full-on girlie day, getting to play dress-up at this level. When you look at just how much work goes into pieces of art like these, you can't help feeling both lucky and beautiful for the moment."