This kid is just too adorable.
"Ace has stolen my heart," the fashion mogul captioned the pic, which showed her 7-month-old wrapped in a blanket and pouting (like his big sis Maxwell!) in a car seat.
The doting mom-of-two has been posting several pics of her little ones as of late, revealing more sweet family shots on Instagram last month.
In one shot she can be seen cuddling Ace, which she captioned, "Ace is the place that I become the annoying kissing mom. All I want to do is snuggle this lil emotional perfect soul! He is a dream!"
Simpson has also been showing off her hot post-baby bod, sharing a sneak peek for her latest Weight Watchers ad, in which she sports a sleek, body-hugging black dress.
Speaking of the weight loss brand, the singer recently dished on how the program helped her shed her pregnancy pounds twice.
"I believe in it with all of my heart," she told Good Morning America's Lara Spencer. "It's a lifestyle. I've tried so many different diets, and you can only stick to something for so long. I feel like with Weight Watchers, it just becomes a part of who you are."
And it shows!