In the snaps, the high school student dazzles in an elegant silk gold slip-dress which she teamed with a gold glomesh purse, a simple gold bangle, gold earrings and a gold necklace.
She finished off her look by sweeping her brunette locks into a messy up-do and opting for a smokey eye and a nude lip.
Cass' post was quickly inundated with touching comments from supportive friends, pointing out just how much Willow looks like her.
"Such a beautiful lady. She looks exactly like you," one person insisted.
"Wow….. stunner. So much like you when you were that age. Hope you are well xx," another friend agreed.
"She is gorgeous love can see Karl in her in one of these but she is you … glamorous," a third mused.
"She is a beautiful young lady. Proud mumma I'm sure," one person said.
While Karl would have no doubt loved to have waved his daughter off, the Today star unfortunately had to miss out on the family milestone due to being in Queenstown for the breakfast show.
Cass shares Jackson, 22, daughter Willow, 16, and son River, 14, with ex-husband Karl.
In May last year, Karl welcomed his second daughter, Harper, with wife Jasmine Yarbrough.
WATCH: Karl Stefanovic gets emotional over baby present for Harper on Today show
This story originally appeared on our sister site, Now To Love.