Phil Mickelson has spent the last two decades buying up a San Diego neighborhood, The Post has learned.

Located in upscale Rancho Santa Fe, the American pro golfer is no stranger to the area.

The native Californian grew up between San Diego and Scottsdale, Arizona. But in 2001, he purchased his first home in Rancho Santa Fe for $6 million, later selling it at a loss for $5.75 million in 2015.

But by that time, Mickelson, 52, who has a net worth of a whopping $875 million, had owned three other properties in the area.

The first two he purchased for a combined $14.1 million in August 2005, records show. Specifically, a main five-bedroom, six-bathroom residence occupying over 13,000 square feet on about 6 acres, and a parcel of land spanning 4 acres.

Four months later, in December 2005, he purchased another parcel of land, made up of 4 acres, for $3.4 million.

Fifteen years later, in 2020, Mickelson had his eyes set on the properties surrounding him. But not all were for sale, until he made the owners of the home next to his an offer they couldn’t refuse.

Sources tell The Post he wanted the home desperately and shelled about $25 million for a four-bedroom, four-bathroom estate set 4.3 acres of land.

Mickelson then splashed out another estimated $25 million for the other adjacent parcel of land, pegged as “one of the few remaining homesites in the exclusive Covenant in Rancho Santa Fe.” The 6.79-acre lot initially listed in 2021 for $12 million.

Sources tell The Post Mickelson has also attempted to buy the estate of Steven Black, the Chairman of Cisterra Partners, but so far to no avail.

“The desirable Rancho Santa Covenant has so much to offer; world class Golf and Tennis Clubs, top rated schools, charming village with shopping and dining, walking/riding trails, high speed internet (fiber) and is just minutes to world class golden beaches, and all major freeways and shopping centers,” the previous listing noted.

According to the same sources, he is working to develop his “dream compound,” which will end up costing upwards of $100 million.

Mickelson has played for the contentious LIV Golf League prior to its shocking merger announcement with PGA this week.

When news of the merger broke, Mickelson reacted with just three words: “Awesome day today ”

When contacted by The Post, a rep for Mickelson declined to comment.