The unknown, and deep-pocketed, buyer of Palm Beach’s only private island has been unmasked.

According to people familiar with the situation, the individual who shelled out $150 million for Florida’s Tarpon Island is an Australian infrastructure investor named Michael Dorrell, as first reported by the Wall Street Journal.

The sky-high sale of 10 Tarpon Isle, the posh town’s only private island, was officially recorded last Friday and set a new record for lakefront properties in the area, The Post previously reported. (It actually sold at a significant discount, having been most recently listed for $187.5 million, making it the most expensive home ever marketed in Palm Beach’s MLS.)

Even before Dorrell’s identity was revealed, it was rumored that he had already begun living at the approximately 2-acre property’s 29,000-square-foot mansion.

Currently, Dorrell is the chairman and CEO of Stonepeak, an infrastructure investment firm based in New York. Previously, he was Blackstone Group’s infrastructure arm’s senior managing director.

The Oz-born buyer has previously made headlines for other eye-wateringly expensive real estate purchases, including spending $34 million for a waterfront teardown in Coral Gables, Florida and $41 million for an Upper East Side townhouse he bought from billionaire David Koch’s widow, Julia Koch.

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