The amicable exes were pictured alongside middle daughter Scout earlier this week as she marked the landmark birthday.
Moore, 58, posted a photo to her Instagram of her and Willis standing either side of Scout.
She captioned the image: "So much fun celebrating our @scoutlaruewillis 💕."
The actors, who were together for over 10 years, are also parents to Rumer, 32, and Tallulah, 27.
Scout had also shared the same image to her own page, joking she was the result of a "very rare" collaboration between her parents.
"30 years ago today the V* rare 2 of 3 DemiXBruce collab dropped," she wrote.
Watch: Demi Moore shows off fit figure in bikini photo
Moore had previously shared a touching post celebrating her daughter, saying she was "honoured" to be her mother.
"You were already carving out your unique path when you decided to arrive 3.5 weeks early 30 years ago," she said.
"You continue to do so with every courageous, thoughtful, and meaningful move you make in this life. I learn from you everyday. I am inspired by you. I really like you. And I am honored to be your mother. Excited to be sharing this life with you. I love you madly!
"I can’t wait for the adventures of the next monumental 30 years - starting with the magic of today, your birthday! 🥳👏🎉 Happy 30th birthday, Scout LaRue ❤️❤️❤️ Loving you to the moon."
Willis, 66, remarried to model Emma Heming in 2009 with the pair going on to have two daughters, Mabel, nine, and Evelyn, seven.
Moore was married in 2005 to Ashton Kutcher, from whom she split from in 2011. In 2019, the Ghost star said she had suffered a miscarriage while six months pregnant during their relationship.
Watch: Ask Anna - How do I move on with someone else after a nasty break-up?