Anna, 33, also shared her own post with a photo of herself and Tim at the exact moment they learned they'd be having a daughter.
"The moment you find out you’re having a girl #purehappiness #genderreveal." she penned in her caption.
Both Tim and Anna's families were all there to witness the exciting news and even Anna's younger sister Charlotte who is based in New York was able to FaceTime her family and be part of the action from afar.
The event featured stunning floral arrangements from one of Sydney's top florists Kashaya & Co
Anna herself was every inch the stunning mum-to-be dressed in an Alice McCall white mini dress and high heels proudly cradling her baby bump.
Meanwhile, dad-to-be Tim donned a denim blue shirt and black jeans for the occasion.
"LOVE IS IN THE AIR," Anna said in her caption as she shared more pictures from the gender reveal party.
"What a weekend!!! Finally had a moment to take it all in. Thank you for all the beautiful messages, we are beyond ecstatic to be having a baby girl."
Tim and Anna, who fell in love whilst filming the first season of The Bachelor Australia in 2013 took bets with their friends and family to see if they'd be having a boy or a girl.
Both shared snaps to their respective Instagram accounts of their loved ones holding up signs that read either boy or girl.
And it seems the family had it right - 25 members voted that Tim and Anna would have a girl whilst 19 thought that they would be having a baby boy.
Baby Robards, who is due in November this year, is the fourth Bachie baby to be born from relationships formed on the hit reality dating show and also the fourth baby girl. There's something in the water clearly!