The first lady sported the Sleeveless Chiffon Dress in Navy Floral, which retails for $39.99, over the weekend during a tour for her "Let's Move" campaign in Florida.
The first lady wore the dress to dinner at the Halls family's Ocoee, Fla., home, accessorizing it with a bright blue cardigan and trading the gold belt for a red one of her own.
The first lady has been known to mix high-priced designer items from designers such as Wu, Lanvin and Isabela Toledo, with pieces from retailers like J.Crew.
Wu's Capsule Collection for Target includes delicate dresses and tops, pleated skirts, scarves, handbags and clutches, all for $60 or less. Items from Wu's regular line can cost $5,000 in luxury department stores.
The young designer has Michelle Obama to thank for putting him on the map. The first lady famously wore Wu's white, one-shoulder silk chiffon dress to President Obama's 2009 inaugural ball, catapulting the designer into the national spotlight. That dress is now on display at the Smithsonian's National Museum of American History in Washington, D.C.
Since then, the first lady has continued to wear Wu's designs, notably a magenta dress on the March 2009 cover of Vogue, and a Wu dress and cardigan to an event with the G20 spouses in April 2009.
The first lady is also a fan of Target. She was seen at suburban Virginia Target in September, where she reportedly bought food and toys for first pooch Bo.
ABC News' Katie Kindelan contributed to this report.