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.
Ugandan-Australian actress Suzan Mutesi also voiced her support, comparing the 34-year-old to an Aussie hunk.
"Is that Chris Hemsworth’s brother!! I like it, Thor vibe!" she wrote.
Another user all but called Matt a hipster, asking him when he was opening his "Açai Brothers franchise".
The Bachelor alum took it in his stride, replying "after I get my sleeve".
While many other comments were digging the look (while also making Braveheart, Survivor and Outlander references), others were convinced they could see some red in the scientist's hair that wasn't there before.
I didn’t realise your hair had a red tinge gorgeous!" one user wrote.
Matt was quick to clarify, replying "only my beard has the ginger. I warmed the colours on the pic a bit so it didn’t have such an unnatural white/blue look so my hair doesn’t quite have the strawberry tinge 😞".
Last year, Matt revealed to Bounty Parents that, since leaving The Bachelor he has tried to control what parts of himself he shares online.
WATCH: Matt Agnew talks about his mental health after filming The Bachelor (Article continues after video)
"You are putting yourself out there and you are subject to a degree of scrutiny and commentary. Being in the public eye with things I am passionate about like science and space, means that I’m not opening up about the private parts of my life so much, it’s a more controlled degree of exposure to the public," he explained.
As for Matt's dating life, considering he's keeping a lid on his private life, we just may never know his relationship status since breaking up with Chelsie McLeod. But, he did tell Bounty that dating wasn't on his radar for the time being.
"I take a while to bounce back from break-ups, so it’s just something that hasn’t been a priority while I’ve been looking after myself."