Jeff Bezos Buys Florida Neighbor's Mansion For $79 Million

Jeff Bezos is expanding his real estate portfolio ... dropping 8-figures for a sprawling estate in Florida's "Billionaire Bunker" island ... and it's next door to a house he already owns.

The Amazon founder plunked down $79 million to buy his neighbor's 19,064-square-foot mansion in Indian Creek ... a barrier island in Biscayne Bay that's chock full of billionaires.

Jeff's new place has 7 bedrooms and 14 bathrooms and it comes with all the bells and whistles ... we're talking a home theater, wine cellar, library, maids' quarters, pool and sauna.

Lauren Sanchez's fiancé even got a discount on the property ... the estate was previously listed in May for $85 million, and Jeff bought it Thursday for $6 mil less.

Jeff reportedly bought a 3-bedroom home next door to this new one back in August for $68 million in an off-market deal ... so it will be interesting to see what he does with the neighboring properties.

Anyone else smell a billionaire compound in the making?

All of the homes in Indian Creek are on the water with boat docks ... and we all know Jeff and Lauren love a good yacht.