"39 with my ladies ?," Jessica captioned a group shot of all of her friends chilling out in the backyard on Instagram.
The mother of three and her gal pals all rocked cool shades and sun hats for the photo.
Jessica flashed a peace sign as she sat on a Louis Vuitton-print covered chair.
She shared another snap of herself leaning onto a large gold ball and gazing into the camera. "39 is all mine!!!" she wrote alongside the gorgeous pic.
The author sported a sexy leopard print bikini and a matching coverup for her birthday bash. Jessica kept it glitzy with her large gold hoops, long chain necklace and rainbow bejeweled sunglasses.
The actress wore her blonde tresses in a cute half-up, half-down style.
Jessica also celebrated her special day with a book announcement on Wednesday. She announced that she will be penning a memoir about her life as a mother, divorce and her fashion career.
What are your thoughts on Jessica's birthday party? Sound off in the comments below!