His maiden post on the social media website was a video showing him engrossed in a Spider-Man comic titled The Return Of The Man Called Mysterio!
Though this is Sony's third take on Spider-Man, with Tobey Maguire and Andrew Garfield having previously portrayed the webslinger in the Spider-Man trilogy and The Amazing Spider-Man respectively, the current Spider-Man is the first to be included in the Marvel Cinematic Universe.
In the video, Gyllenhaal appears to be very shocked and mouths the words, "Woah". His appearance in Spider-Man: Far From Home marks the character's live-action debut.
Trump keeps up pressure on Democrats over border wall
Previously, Trump threatened to force a partial government shutdown if Congress did not give him the money he wants for the wall. Trump claimed in a tweet that "We would save Billions of Dollars if the Democrats would give us the votes to build the Wall".
Tom Holland, who has been playing the Spider-Man in the new series, couldn't help but join in. But marketing these films without spoiling the most important one of the three will be hard, a new report notes, and Sony is already hiding potential Avengers 4 spoilers from Spider-Man 2 marketing.
Jon Watts is returning to direct the sequel to Homecoming, which earned $880 million (£656,216,000) worldwide.
"I just realized I'm not playing Spider-Man", reads the caption. He is next set to appear in Edward Berger thriller Rio alongside Michelle Williams and Benedict Cumberbatch, and is in the pre-production phases of crime-thriller Finest Kind.
Spider-Man: Far From Home will be released in the United Kingdom on July 5, 2019.