Reese Witherspoon wishes 'incredible' daughter a happy 21st birthday in sweet tribute

Reese Witherspoon and her daughter Ava.
Reese Witherspoon and her daughter Ava. Photo: Instagram

Reese Witherspoon has wished her daughter Ava a happy 21st birthday, posting a sweet tribute to her mini-me on Instagram.

"Wow! How is it possible that this little girl is now 21 years old?" Witherspoon wrote in the sentimental post.

"Happy Birthday to my sweet girl who has become the most incredible young woman. Her kindness, her compassion, and her huge heart never cease to amaze me," the actress continued.

"Ava, there aren't enough words to describe how proud I am of everything you've already accomplished. I cannot wait to see ALL the Good you will put into this world..." she concluded the post.

The Oscar-winner shares Ava and son, Deacon, 16, with ex-husband Ryan Phillipe.

The pair met in 1997 and married in 1999, the same year she gave birth to Ava. They divorced in 2007, with Witherspoon marrying talent agent Jim Toth in 2011, giving birth to her third child, Tennessee in 2012.

Witherspoon previously admitted that juggling motherhood and her career at a young age was "scary', but she's glad she had children young.

I got pregnant [with Ava] when I was 22. I delivered when I was 23. To be totally honest, it was scary. I was scared. I didn't know what it was going to do to my job or my career. Your entire life will change," she said in a video on her Reese Witherspoon x Hello Sunshine YouTube page.

"I find having little kids is more physical and it's just really hard on your body. So, I am glad that I had kids kind of young," she says. "I had one at 23, one at 27 and then again at 37. And, oh, my God, having a baby at 37 was so much harder."

"This is just me being real," the mum-of-three continued. "Everybody's life experience, you have to do when it's right for you."