Josh Brolin's officially parting ways with his gorgeous Georgia home ... TMZ has learned.

A real estate source tells TMZ the sale closed Wednesday ... and the buyer, who shelled out $4 million to snag the place, isn't another celebrity.

The massive mansion boasts 7 beds and 11 baths ... and it comes with all the bells and whistles.

Take a look ... there's a screened-in rotunda with a grill, fireplace and plenty of places to lounge.

Not to mention, the kitchen is a chef's dream, and the 2-story living room is about as cozy as it gets.

The crib also comes complete with a professional-grade gym equipped with both a sauna and a cold plunge.

There's also a home cinema, a grand staircase to the second floor, and a detached, 2-story guest house.

And you gotta check out this pool ... not only is it heated and stunning, but it's also got a hot tub, 2 waterfalls, and a rock you can jump off.

Jacob Bean of Studio Housing Atlanta held the listing.

We're told Brolin said goodbye to the posh pad because he's planning to ditch the South and move back to California.

Check out our gallery to see what the new owners are getting.