Former "The Real Housewives of Beverly Hills" star Yolanda Hadid's baby girl turned that all important age of 21 years old on Oct. 9, and her mom wasn't about to let the occasion slip by without raising an online toast to her daughter.

Rex USA

Yolanda shared a throwback image of her holding up Bella as a baby.

"Happy birthday my sweet angel..... You are my everything!" she captioned the image. "Born with so much wisdom and a heart full of compassion like no one I've ever met before. You are a mirror and teacher off all things fair and equal. I admire your ability to always see the good in everything and everyone......"

She added, "Never stop shining bright my love, your pure light is contagious. Thank you for being YOU and loving me the way that you do, I am so proud to be your mommy...... #AlwaysAndForeverYours."

The online tribute came a day after Bella's fellow model sister, Gigi Hadid, also took to Instagram to publicly honor her sister.

"TOMORROW WILL BE 21 YEARS SINCE I MET MY FOREVER BESTIE @bellahadid," she captioned an image on Oct. 8.

In the image, a youthful Gigi can be been seen hugging baby Bella. Gigi joked about the image, writing, "me wearing all red on your actual day of birth is MAJOR and possibly the reason it's your favorite color 😜 ."

In her Instagram story, Gigi also posted a drawing that she made in 2001. The drawing featured Bella with a birthday cake, hat and balloons. "Tomorrow is my sister's birthday. She is turning 5," it said.

Bella reposted the drawing to her Instagram story with multiple heart and twin emojis, writing, "BEST FRIENDS FOREVER. MADE ME CRY. LOVE YOU @gigihadid."