She regularly sports bright-colored cardigan sweaters topped with wide belts, sometimes layered over a blouse or lighter sweater. She is modern yet feminine, pairing bold-patterned skirts with flats or low kitten heels.
Her signature go-to accessories include bold-statement jewelry; large necklaces, colorful brooches and an armful of bangle bracelets.
Mary Tomer, who in September 2008 created a blog in September 2008 dedicated to the first lady's fashion and style, said Obama's "range and adventurous spirit" are the most defining characteristics of her style.
"In 2007 and 2008, Michelle Obama's style was almost synonymous with the fitted sheath dress, a belt at the waist and a classic strand of pearls," Tomer said. "In the White House, we've seen Mrs. Obama branch out from that, embracing an adventurous sense of style that includes everything from full skirts to off-the-shoulder tops."
Perhaps her most well-known fashion statement; the daring decision to bear arms.
The first lady's toned biceps and triceps have been the subject of countless columns and articles, fitness routines and watercooler discussions among women of all ages. She is not afraid to wear sleeveless dresses and even posed for her official White House portrait in a sheath dress by Michael Kors that showed off her buff physique.
Another key element of Obama's style is her ability to mix high-end fashion with items from everyday retailers that the average U.S. woman can afford.
She has drawn rave reviews for her creative balance of high-priced designers such as Jason Wu and Isabel Toledo and moderately priced wardrobe pieces from retailers such as J. Crew, Talbots, White House/Black Market and even Target.
Such fashion choices, compared to previous first ladies, make her relatable, fashion editor Givhan said.
"Women look at her and they see more of themselves in her than they would perhaps, you know, someone who dressed more like a traditional first lady," she said.
But, Givhan added, the style also makes her more open to criticism.
"She dresses with personality," she said. "And when you dress with personality, some people are going to embrace that with incredible enthusiasm, and then there are going to be others who not so much."
Blogger Tomer said there is a "degree of direct influence" that the first lady's fashion decisions have on the average U.S. woman.
"The belted cardigans, pencil skirts and brooches are a few styles American women have adopted," she told ABC News. "And, certainly, I think everyone is working out their arms a bit more."
The mixing and matching of high- and low-end clothing can sometimes cause trouble, as the first lady learned in the spring.
At a public service event at a Washington D.C., food bank, Obama went for a casual look, sporting a sweater and capris pants, as well as a pair of pricey, suede/metallic/pink sneakers from French label Lanvin.
The Lanvin sneakers were available in a variety of colors at Barneys and other high-end retailers and cost a pretty penny at $540.
The sneakers did not fit into the image of Obama as an everyday mom and seemed especially inappropriate given the nature of the event.
The Washington Post's Givhan said at the time that the sneakers were not something to get into a "tizzy" about when one puts the first lady's fashion into context.