She's now keeping company with the Duchess of Cambridge, Diane Kruger and Jay-Z.
"I was shocked I was on the list. I have no idea how I got on it, but now the pressure is on!" she says.
Wiedemann makes some thoughtful wardrobe choices, and, yes, she has some close industry friends, but she's pretty practical and spends a lot of time in workout and weekend clothes.
She opened up her closet to The Associated Press, sharing her secrets as a thrifty shopper, ideas about what might come after modeling and how she justifies her collection of pricey Repetto ballet flats. All the while, she's casual and relaxed in bare feet, jean shorts and a red tank top.
"I'm not an impulse shopper," says Wiedemann. "I will wait three days after I see something. Am I still thinking about (it)? Then I'll get it."
Those $200-plus Repettos? She wears them almost every day. "I'm not a Carrie Bradshaw."
She indulges in good sneakers because she's training for her third triathlon. Anyway, the kicks match the athletic gear she's wearing most days. As a model, she explains, she's largely paid to stay in shape and eat well. (She did complete a Master's program in biomedicine from the London School of Economics, with a dissertation focusing of vertical farming and the future of agriculture.)
She took up Ironman-inspired exercise to try something new.
"I was so sick of training for 'my job' and doing ballet leg lifts—which are so boring," she says. "If I'm going to be working out two hours a day, I may as well have a goal ... and I'm pretty competitive by nature. A triathlon is a new fun thing."
Not that she's down on fashion. On this day, she's headed to a launch party for Prabal Gurung's new collection for ICB, and she'll be in the front row at the shows of her friends at New York Fashion Week, which began Thursday.
Among her other recent wardrobe additions are knit Urban Zen pants and a canvas Lands End tote bag. When she does shop, she's mostly looking for clothes that have multiple uses. "I want something to wear for lunch with my grandparents or for a night out with my husband."
Her other favorites: luxurious silk Equipment-brand button-down shirtdresses in every color of the rainbow that, she says, are a traveler's best friend, and a neon pink dress that she picked up at a vintage shop. A Rick Owens leather jacket is one of her most prized possessions. "I'm sad in the summer when I can't wear it."
She lives in a one-bedroom apartment in Manhattan's West Village with her husband, James Marshall. Given the small space, Wiedemann says she and Marshall don't quite split it equally.
"My side is a little bigger, but I also have the sheets on my side," she says with a smile, opening the doors to custom-made built-in storage units that fill about one-third of her room.
It's all neatly arranged, and that's part of her strategy.
"I think it's part of my Swedish genes," says 29-year-old Wiedemann, a granddaughter of the late Ingrid Bergman. "I like things clean, and I have a biannual clean-out of my apartment. I throw out raggedy things and things I never wear, and there's a Goodwill around the corner for anything worthwhile."
She adds, "I used to be more sentimental about 'things' but as I've gotten older that matters less."
She's also grown wiser about her sense of style, Wiedemann says, embracing the occasional "Wow!" piece and pop of color, but otherwise embracing chic dark sweaters, timeless denim and workhorse black trousers.
What you don't see are a lot of evening gowns even though her calendar is booked with many black-tie events and celebrity parties. For those, she borrows from industry friends.
Where would she keep her own gowns? Wiedemann wonders aloud.
Back in May, wearing a red satin Sophie Theallet gown, she hosted a live stream of the red carpet at the Metropolitan Museum of Art Costume Institute Gala—known in fashion circles as "the party of the year"—for Vogue and found herself interviewing A-list stars.
"When Vogue asked me to do it, I said, 'Oh, yeah, sure. No problem.' I'm glad I didn't think about it because then I'm not sure I would have said yes, but I had gone to the Met ball as a guest before, and it's one of the best nights," she says.
It's not like she's hunting for a TV reality show, but, Wiedemann says, she wouldn't rule out more hosting gigs. Hmmm, she muses: A change in careers would allow her to enjoy those calorie-laden daiquiris her husband seems to enjoy on their beach vacations.
The plan wasn't necessarily for her to be a model. Yet, she says, she's been financially independent thanks to her work in front of the camera since the age of 19.
And, as long as magazines, fashion houses and big beauty brands are willing to pay her, they won't hear any complaints about what she's asked to wear. "I don't speak up if I'm working. As a model, no one pays me for my opinion," she says. "I want to wear whatever will make a great photo, whether I like it or not. But if the shoes are too small, I will complain!"