In a special touch, the actor added a second caption which read: "I guess I'm more similar to Will than I thought."
He is, of course, referring to his Stranger Things character Will Byers who has been queer coded since season one of the hit franchise.
The comments were overwhelmingly supportive of the teen actor, with Netflix sharing three heart emojis, while fans and friends alike expressed how proud they were of the star.
Noah's best friend and fellow Stranger Things actor Millie Bobby-Brown has yet to publicly comment on the news, but no doubt she has been supporting him behind the scenes.
Stranger Things officially premiered on the streaming giant in 2016 to huge success. Noah was the youngest of the cast members, just 10 years old when season one began.
Will's sexuality has always been a huge talking point amongst the fandom.
Last year, Noah confirmed to Variety that Will is gay and in love with his best friend Mike Wheeler (Finn Wolfhard).
“It was always kind of there, but you never really knew, is it just him growing up slower than his friends?” Schnapp said.
“Now that he’s gotten older, they made it a very real, obvious thing. Now it’s 100% clear that he is gay and he does love Mike.”