"A reminder to not care too much what I look like because no matter how much effort I put in, I’m going to cringe at myself in a decade," she captioned the post.
"Also to anyone in high school, don’t care too much what boys think of you because you will look back at photos in 10 years and have to use every last brain cell to remember their names.
"No one ever let me wear a dark blue Smokey eye with a light beige lipstick and black box dyed hair ever again," she joked.
Abbie's 298,000 followers were impressed by her "glow-up", while others said they preferred the 26-year-old as a brunette.
"I actually love the dark hair!!!! I never thought I’d say that but your eyes look sooo amazing," one fan wrote.
"Wow you look stunning as a brunette also!" said another.
"Ok but this is cute and iconic," another comment read.
Abbie's throwback comes after Matt Agnew, whom she dated on the 2019 series of The Bachelor, shared his unrecognisable new lockdown look.
The astrophysicist-turned-reality star took to his Instagram to share the results of a months-long barber ban and seemingly no attempts at a DIY job.
Posting a photo of his lengthy and slicked back man bun, coupled with a full beard, the astrophysicist wrote, "Tell me you’re in lockdown, without telling me you’re in lockdown".
The debuted look had a mostly positive reaction, but firmly on board was Matt's fellow Bachelor boy Sam Wood who wrote "Suits you mate" in response.