KJ announced her new tequila line Tuesday -- which she's dubbed "818," the area code in Calabasas -- while going on to explain the years-long journey she's been on to get to make what she considers the best spirit.

She writes, "after dozens of blind taste tests, trips to our distillery, entering into world tasting competitions anonymously and WINNING (🥳) ..3.5 years later i think we’ve done it!"

Kendall added this too ... "this is all we’ve been drinking for the last year and i can’t wait for everyone else to get their hands on this to enjoy it as much as we do! @drink818 coming soon 🥃🤤"

She attached a video of herself doing a taste test, which appears to have led to a final approval of her new product. There are also photos of her and friends downing her concoction, plus photos of a bunch of harvested agave plants.

This isn't a total shocker, BTW -- there've been subtle hints ... especially based on photos she posted from a recent getaway down to Mexico.

It also looks like 818's been in a bunch of tequila competitions recently (winning several) ... but has yet to hit the market widely. Up until now, there was a ton of buzz over 818 -- but no one knew how to get it, when it would officially launch or who was behind it.