The "Dhadak" actor posted a photograph in which he is seen executing the dangerous stunt. It was taken in Grossglockner in Austria.
"Somewhere 6,223 kilometres away," he captioned it.
While some suspected it to be photoshopped, other couldn't stop praising him and calling him Spider-Man.
One fan even tagged actor Tom Holland, who plays Spider-Man in the latest set of Marvel movies, and wrote that Ishaan could give Holland a run for his money.
Another broke into a Hindi song: "Isspiderman tumne churaya mere dil ka chain". Others simply called him "Hey Spider-Man".
Ishaan is currently on a bike tour with elder brother Shahid Kapoor and actor Kunal Kemmu.