Kim Zolciak was feeling grateful on daughter and "best friend" Brielle Biermann's 21st birthday.

The 39-year-old television personality dedicated a series of throwback photos and a sweet message to Brielle on Instagram while celebrating the occasion Sunday.

"Dedicating today to my beauty @briellebiermann the very person that gave me strength to keep pushing! I had Brielle at almost 19, I was so excited I could barely stand it but I was a nervous wreck at the same time!" Zolciak captioned the slideshow.

"My side kick, My heart, My strength, My pride and joy, My best friend, My daughter YOU amaze me!!" she gushed.

"We made it Elle I always knew we would. You are such a blessing to this world! Thank you for making my 'job' as your mom an easy one!"

Brielle rang in her birthday with friends Saturday at Prime 112 restaurant in Miami Beach, Fla.

She shared photos and videos on social media throughout her birthday weekend, including pictures of herself holding "21" balloons.

"20? I don't know her," the star wrote.

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Zolciak is mom to Brielle and 16-year-old daughter Ariana from previous relationships, and shares 6-year-old son Kroy Jr., 5-year-old son Kash and 4-year-old twins Kaia and Kane with husband Kroy Biermann.

"Brielle you are one of the BEST 'things' that has ever happened in my life! I AM SO PROUD OF YOU!!!" she said in a post Saturday. "I love you far beyond words could ever describe!"

Zolciak is known for starring on the first five seasons of "The Real Housewives of Atlanta," and returned as a friend of the housewives in Season 10.

She and her family also star on the Bravo series "Don't Be Tardy."