The "Breaking Bad" star rang in the big 4-0 in the DR ... and he spared no expense, staying in a suite at The Ani Resort that goes for $25,000 a night. Aaron shacked up for 12 nights, dropping $300k just for his lodging!!!

Aaron was rolling deep ... he had his better half with him, plus his family and close friends, including Bryan. We're told the "Breaking Bad" costars spent their time sipping their new Mezcal that just launched, Dos Hombres.

Rum's usually what you think of when you picture a boozy drink on a Caribbean beach ... but when you've got your own liquor brand, you play by your own rules!!!

Aaron and co. had a rocking time ... soaking in all the resort and island have to offer ... infinity pools, perfect weather, soft sands, amazing food, crystal-clear seas ... the whole shebang.

Blowout birthday parties are kinda Aaron's thing ... when his wife turned 30 back in 2016, Aaron rented out a massive private villa in Thailand just for the 2 of them.