The actress shared photos of her teenager to Instagram, writing simply '#18' on the first, before sharing a long, heartfelt message on a throwback photo of Ava when she was younger.
"Happy 18th Birthday to my sweet girl @avaphillippe!," the actress wrote. " 🎂Your kindness, grace, intelligence and humour never cease to amaze me. I love you and your HUGE ❤️ and I feel so lucky that I get to be your mum."
Ava also took to social media to celebrate her birthday, posting a photo of the amazing present her mum had given her: 18 letters which she had written each year to commemorate Ava's birthday.
"18 letters that made me cry (hard) today, courtesy of my lovely mother," she wrote.