The 35-year-old fashion entrepreneur showed off her slim physique and enviable abs in a tight-fitting cobalt blue Cushnie Et Ochs ensemble on Saturday night with her husband, Eric Johnson. The couple attended a friend's birthday party along with Jessica's younger sister, Ashlee Simpson Ross, and her brother-in-law, Evan Ross.
Clasping hands with her hubby while leaving the bar in Sherman Oaks, California, Jessica accessorized her show-stopping outfit with nude platform heels and a bright purple purse.
But if you want Jessica's designer outfit, it's going to cost you -- the stretchy knit crop top retails for $695, while the matching skirt sells for $595, totaling a whopping $1,290.
The party of at least 30 celebrated in a private room, with Eric buying everyone shots at one point, an eyewitness tells ET about the fun night out. The couple left around 12:30 a.m., with Jessica appearing to be in a "great mood."
The mother-of-two has had no problem flaunting her slim figure as of late, slipping into a pair of daisy dukes for a girls trip to Mexico late last month.
When ET chatted with Jessica in January at the YMA Fashion Scholarship Fund Awards Gala in New York City, she credited being an active mother to her daughter, 3-year-old Maxwell, and her son, 2-year-old Ace, as the main reason for her awesome physique these days.
"I think being a mom is enough of a diet," she smiled. "You have to run around chasing your kids, but I do eat a lot of their corn dogs, so I have to get on the treadmill a lot to watch my TV shows."