The 39-year-old actress, shared a cute happy birthday post on Instagram as her daughter turned 16, reported Hello! magazine.
Reese posted a side-by-side photo of Ava as a little girl, and now.
"Wow! My sweet girl turns 16 today. I am so blessed to have such a kind, compassionate, brilliant, artistic, all-around wonderful daughter who makes me a better person every day," she wrote.
The "Wild" actress was 23 when she gave birth to Ava, after tying the knot with her "The Cruel Intentions" co-star Ryan. The couple, who also have a son together separated in October 2006.