“Happy 18th Birthday to my sweet girl @avaphillippe!” the Legally Blonde actress, 41, captioned a throwback pic with her look-alike daughter. “Your kindness, grace, intelligence and humor never cease to amaze me. I love you and your HUGE [heart] and I feel so lucky that I get to be your mom. #proudmom #18.”
Phillippe, 42, also shared a series of pics of his daughter on Instagram.
“Happy birthday, punk,” the Shooter star wrote. “I love you more than any strangers need read, but… you are the coolest smartest most beautiful daughter a father could ever have and even though you’re no longer a child, you’ll always be my little girl. Happy 18th, princess.”
Ava also shared a beautiful throwback pic of herself dressed in a yellow princess gown and posted a photo on Instagram of one of 18 letters that her thoughtful mom had written to her daughter each year, saving them to be opened on her landmark birthday.
“18 letters that made me cry (hard) today, courtesy of my lovely mother,” she wrote.
Witherspoon and Phillippe met at her 21st birthday party in 1997, marrying in June 1999. Ava arrived later that year and the couple welcomed son Deacon in 2003.
They split three years later and Witherspoon went on to marry talent agent Jim Toth in 2011. They have a son Tennessee, who turns 5 later this month.
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!
For the latest celebrity entertainment, news and lifestyle videos, subscribe to Us Weekly’s YouTube Page!