The first-time GRAMMY nominee, who took home three awards last night, stunned in four looks total. First, she channeled Marilyn Monroe vibes in a white Swarovski crystal-embellished bustier gown accessorized with a faux fur stole -- a custom ensemble by none other than Atelier Versace.
"The work that was behind this dress. I saw the inside of it. It was insane," Nelson gushed to ET's Marisa Runyon on Monday morning.
"This was her night. It's everything. It was Lizzo's GRAMMY night. From the carpet looks that she did to the opening of the performance, it was all so magical."
Following the red carpet, Lizzo opened the show with a gorgeous medley performance. The 31-year-old star graced the stage in a breathtaking custom Christian Siriano black off-the-shoulder gown that boasted crystal embroideries all over as she belted "Cuz I Love You" with an orchestra playing behind her.
"I was super inspired by an operatic ball gown. She was the conductor of this group of beautiful women," the stylist explained. "I wanted it to sparkle like a galaxy. There's a lot of glitter onstage and there were little dots of sparkle all over the whole entire dress."
Nelson also revealed he only had a week to put together Lizzo's looks for her big night.
"We only had three times [of rehearsal]. It was bit of a stress -- the camera block that we did 'cause the zipper busted. It was kind of rushed to figure it out. You can't mess up, it's on TV," he shared.
Lizzo then sped up the tempo with a lively, heart-pounding performance of her breakup anthem, "Truth Hurts," after changing into a futuristic, multicolored bodysuit by Croatian designer Zigman in "less than 48 seconds." The custom piece was adorned with, you guessed it, more crystals.
"We completely crystaled it. Swarovski came on board as a sponsor with it, so the whole entire performance had I think, like, 250,000 crystals onstage," Nelson said.
Nelson also praised Lizzo for staying true to her sexy style.
"Lizzo likes to feel sexy and sometimes people don't know how to dress a bigger girl and they just want to put them in oversized dresses. It's not the way she wants to look and that's not the way we want to see her either because she's so body positive," Nelson said. "Let's see how sexy she is."
Lizzo also worked with stylist Marko Monroe, who dressed the singer in her fourth and final look -- a sheer crystal fringe maxi that looked like liquid on her body.
"It dripped with her," Nelson spoke of her second custom Atelier Versace piece. "There's other photos of her too where it just looks from the waist down she's completely naked and you see her beautiful legs. A little clear heel. It was pretty damn good."
Watch Nelson, model Iskra Lawrence and drag queen Trixie Mattel recap the best fashion moments from music's biggest night with ET in the video above.