The singer was announced as the winner for Best Pop Vocal Album for "Midnights" Sunday night -- and Tay Tay went up there to accept her hardware ... like we said, this marks her 13th Grammy statuette, something she made a note of right from the get-go at the mic.

Taylor then started teasing some major news -- which got the crowd whipped up into a frenzy. Eventually, she let the cat out of the bag ... T-Swift has a new project coming soon.

She says the forthcoming album -- one she says she's been working on in secret for the past two years, unbeknownst to her fans -- is called 'The Tortured Poets Department,' and it's dropping on April 19.

Shortly after winning her award/making her big announcement ... Taylor went backstage and uploaded a tweet that showed off what seems to be the album cover, as well as some apparent lyrics. They're interesting ... they certainly read like a traditional poem, super deep.

As you can imagine, the Swifties are absolutely losing their minds right now -- 'cause this truly did come out of nowhere. Up until now, people figured she was busy re-recording her old albums and was focusing on just that for the time being.

She released two "Taylor's Version" albums last year ... and seemed to have her hands full on that front. Plus, she's been knee-deep in performing for the "Eras" tour -- not to mention being in a whirlwind romance with Travis Kelce. As it turns out, she was laying down tracks for a whole new project in the wings ... and now, we're going to hear fresh material.

If you thought Taylor was already on top of the world -- and she most certainly is -- that mountain top is only going to get higher at this point. 2023 was Taylor's year ... ditto for '24.