12:04 PM PT -- Taylor was seen cheering on Travis and co. from her luxury box, and it looks like Santa was by her side the entire time. Word is, that's her broski, Austin ... so it's a whole family affair.

No sign of Travis' mom, Donna, here ... but they're saying his dad Ed is in attendance. It also looks like the fans brought out their best Swiftmas posters for the game as well, per usual.

Taylor Swift is back in the building to watch Travis Kelce -- only this time, a couple things are different ... it's Christmas, and her mama is there too for the very first time.

Big day in Kansas City ... 'cause Taylor could be seen cruising through Arrowhead Stadium ahead of kickoff like she normally does -- but on Monday morning, Andrea Swift was right next to her -- riding in the front passenger seat of a private golf cart driving them around.

Taylor was in it too, but she was in the back ... and both of them waved at people like they were in a parade as they passed cheerful onlookers. Oh, and Santa was there too!

Like we said, Andrea's never been to one of Travis' games with Taylor (that we're aware of anyway) and we honestly haven't seen much of her during T-Swift's romance with the Chiefs tight end. We have seen her dad, Scott, a handful of times ... but no Mama Bear 'til now.

Unclear why that might be the case, but in case it wasn't clear already -- Taylor's parents are divorced ... so that's why Andrea isn't usually right by Scott's side at these sorta outings.

Today, however, it looks like they'll be a united family in front of cameras -- 'cause Scott is said to be there as well ... and we're sure to see them soon enough here in the suite.

This will be the 8th game of Travis' that Taylor's attended ... she's made it a regular thing this season, and her appearances are always memorable -- especially as she gets more into it.

Remember, she's on a break from work at the moment ... and doesn't have to hit the stage again until February when she'll fly to Tokyo for more 'Eras' shows. In the meantime, she's been spending a lot of time with Travis ... including the holidays, minus Thanksgiving.

It's shaped up to be quite a year for her, to say the least. Here's to a couple more games to finish 2023!