The pillar was spotted on Compton Beach, on the west side of the island, over the weekend.
Island resident Alexia Fishwick said the discovery was “really quite magical”.
She said it was “pure chance” that she came across it.
“I’d read about the one in Utah and then Romania, so I knew the significance,” she said.
“Many people took no notice of it.”
She said people first thought she had photoshopped the images.
Lee Peckham, a lawyer living on the island who also spotted the structure on Sunday afternoon, said: “I saw it and wondered what it was and thought it a rather strange thing to see on the beach!
“I wondered who put it there and why.”
A metal edifice was first found planted in the ground in a remote part of Utah at the end of November.
It disappeared just days later, and two other shining metal towers later appeared in Romania and Southern California.
An anonymous collective called The Most Famous Artist has taken credit for the monoliths in Utah and California.
It posted an image of the Utah monolith on Instagram, with a 45,000 US dollar (£34,000) price tag.
However, when asked about the Isle of Wight structure, it said: “The monolith is out of my control at this point. Godspeed to all the aliens working hard around the globe to propagate the myth.”