Documenting the happy day, Brielle shared a series of photos of herself wearing a bedazzled black mini dress and posing with two balloons which showed off her new age.
“20? I don’t know her!” the birthday girl — who recently announced she’s moving out of her mother Kim Zolciak-Biermann’s house — enthusiastically captioned the snaps, which were taken at Miami restaurant Prime 112.
No one was more excited about Brielle’s birthday news than Kim, though.
Sharing one of the same photos as her daughter, the Real Housewives of Atlanta star exclaimed, “[IT’S] OFFICIAL @briellebiermann is 21!!!!”
Affectionately she added, “I can’t believe it!! Happy Happy Birthday Hunni Bunni!! We love you so much!!!!”
But that wasn’t the only birthday tribute the proud mama posted.
Ahead of her daughter’s big day, the 39-year-old shared a throwback photo of the pair soaking up some sun on the beach and jokingly thanked Brielle for “literally sucking the life out of my t——.”
“20 years ago my nugget @briellebiermann and I! Like why did I think being that tan was cute!” she wrote alongside the sweet snap.
Continuing, she wrote, “Brielle you are one of the BEST ‘things’ that has ever happened in my life! I AM SO PROUD OF YOU!!!… What you stand for, who you are, how you live your life, your morals, your values, your beliefs, you have always been a LEADER and you have never swayed! I love you far beyond words could ever describe!”
“Now behave in Miami! and remember alcohol and the water don’t mix! 😉❤ I’ll silently cry myself to sleep 😢,” she jokingly added.
And the sweet birthday tributes kept coming on Sunday, as Kim gushed over the amazing woman her daughter — and “best friend” — had become.
“Dedicating today to my beauty @briellebiermann the very person that gave me strength to keep pushing!!” she wrote alongside a series of adorable throwback photos of the 21-year-old.
“I had Brielle at at almost 19, I was so excited I could barely stand it but I was a nervous wreck at the same time! My side kick, My heart, My strength, My pride and joy, My best friend, My daughter YOU amaze me!! We made it Elle I always knew we would,” she added.
“You are such a blessing to this world! Thank you for making my ‘job’ as your mom an easy one! I truly mean that from the core of my being! I made it through the night last night barely, no sleep worrying about you .. I guess some things will never change no matter how old you get!” she continued.
In a separate post, Kim added, “Still can’t believe you are 21 @briellebiermann 🙈😩🎉🎁😍💋 I feel like I took this pic of you yesterday!”